Doc 6.2, ver.1.0 | March 2018

ALMA Cycle 6 Proposer’s Guide

ALMA, an international astronomy facility, is a partnership of ESO (representing its member states), NSF (USA) and NINS
(Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with theRepublic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.

For further information or to comment on this document, please contact your regional Helpdesk through the ALMA User
Portal at www.almascience.org. Helpdesk tickets will be directed to the appropriate ALMA Regional Center at ESO,NAOJ or NRAO.

Version

1.0

Date

6 March 2018

Editors

Paola Andreani, John Carpenter, Maria Diaz Trigo, Elizabeth
Humphreys, Hiroshi Nagai, Anthony Remijan, Martin Zwaan

In publications, please refer to this document as:P. Andreani et al. 2018, ALMA Cycle 6 Proposer’s Guide, ALMA Doc. 6.2 v1.0

Table of contents
1 WHAT’S NEW IN CYCLE 6 .......................................................................................................... 5
1.1

Technical and observing capabilities ..........................................................................................................................5

1.2

Proposal format ...................................................................................................................................................................5

1.3

Observing Tool features ...................................................................................................................................................5

2 ALMA OVERVIEW ..................................................................................................................... 6
2.1

The ALMA partnership ......................................................................................................................................................6

2.2

The ALMA telescope ...........................................................................................................................................................6

2.3

The Joint ALMA Observatory and the ALMA Regional Centres ..........................................................................7

2.4

The ALMA Science Portal .................................................................................................................................................8

2.5

ALMA proposal eligibility ................................................................................................................................................8

3 PROPOSAL TYPES...................................................................................................................... 9
3.1

Regular Proposals...............................................................................................................................................................9

3.2

Target of Opportunity Proposals ............................................................................................................................... 10

3.3

Large Programmes .......................................................................................................................................................... 10

3.4

mm-VLBI Proposals......................................................................................................................................................... 11

3.5

Director Discretionary Time Proposals .................................................................................................................. 11

4 PROPOSAL PLANNING ............................................................................................................ 12
4.1Time available in Cycle 6............................................................................................................................................... 12

4.2

Summary of capabilities offered in Cycle 6 ............................................................................................................ 12

4.3

Scheduling considerations ........................................................................................................................................... 13

4.3.1
4.3.2
4.3.3
4.3.4

Duplicate observations and resubmissions ........................................................................................................... 19

4.4.1

Checking for duplications ............................................................................................................................................................. 19

4.4

Weather ................................................................................................................................................................................................ 13
Angular resolution ........................................................................................................................................................................... 15
Configuration schedule for the 12-m Array ......................................................................................................................... 16
Observing pressure ......................................................................................................................................................................... 191

4.4.2

Resubmission of an unfinished proposal .............................................................................................................................. 20

4.5

Estimated observing time ............................................................................................................................................. 20

4.6

Supporting tools and documentation ....................................................................................................................... 22

4.6.1
4.6.2
4.6.3
4.6.4

4.7

The Observing Tool documentation ........................................................................................................................................ 22
Additional proposal preparation tools ................................................................................................................................... 23
The ALMA Regional Centre Guides .......................................................................................................................................... 23
Supplemental documentation .................................................................................................................................................... 23

The ALMA Helpdesk ........................................................................................................................................................ 24

5 PROPOSAL PREPARATION AND SUBMISSION .......................................................................... 24
5.1

Proposal format ................................................................................................................................................................ 24

5.2

Preparing the Scientific Justification ........................................................................................................................ 25

5.2.1
5.2.2
5.2.3

Page limits ........................................................................................................................................................................................... 25
Science case ........................................................................................................................................................................................ 25
Figures, tables, and references................................................................................................................................................... 26

5.3

Preparing the Technical Justification ....................................................................................................................... 26

5.4

Proposal validation, submission and withdrawal ............................................................................................... 26

5.4.1

Proposal evaluation and selection ............................................................................................................................ 27

5.5.1
5.5.2
5.5.3

Peer review ......................................................................................................................................................................................... 27
Evaluation criteria ........................................................................................................................................................................... 28
Proposal selection ............................................................................................................................................................................ 28

5.5

5.6

Proposal updates .............................................................................................................................................................................. 27

Proposal confidentiality ................................................................................................................................................ 29

6 POST-PROPOSAL ACTIVITIES ................................................................................................... 29
6.1

Observations preparation and submission: Phase 2 .......................................................................................... 29

6.2

Changes to submitted programmes .......................................................................................................................... 30

6.3

Data processing and data delivery ............................................................................................................................ 30

6.4

Opportunities for public promotion of ALMA ....................................................................................................... 30

APPENDIX A
A.1

ALMA CYCLE 6 CAPABILITIES .............................................................................. 31

Number of antennas........................................................................................................................................................ 31

2

A.2

Array configurations ...................................................................................................................................................... 31

A.3

Total Power Array ........................................................................................................................................................... 32

A.4

Allowed array combinations and time multipliers ............................................................................................. 33

A.5

Receivers ............................................................................................................................................................................. 34

A.6

Spectral capabilities ....................................................................................................................................................... 35

A.7

Polarization........................................................................................................................................................................ 37

A.8

Source restrictions .......................................................................................................................................................... 38

A.9

Calibration .......................................................................................................................................................................... 40

A.10

Time-constrained observations ................................................................................................................................. 41

A.11

Solar observations ........................................................................................................................................................... 42

A.12

VLBI observations............................................................................................................................................................ 43

APPENDIX BTECHNICAL JUSTIFICATION GUIDELINES ............................................................. 45

B.1

Sensitivity ........................................................................................................................................................................... 45

B.2

Imaging ................................................................................................................................................................................ 46

B.3

Correlator configuration ............................................................................................................................................... 46

B.4

Choices to be justified .................................................................................................................................................... 47

B.5

Solar observations ........................................................................................................................................................... 48

B.6

VLBI observations............................................................................................................................................................ 48

APPENDIX CACRONYMS AND ABBREVIATIONS ..................................................................... 49

APPENDIX DSCIENCE CATEGORIES AND KEYWORDS .............................................................. 51

3

Cycle 6 Call for Proposals
The ALMA Director, on behalf of the Joint ALMA Observatory (JAO) and the partner organisations in East
Asia, Europe, and North America, is pleased to announce the ALMA Cycle 6 Call for Proposals (CfP) for
scientific observations to be scheduled from October 2018 to September 2019. It is anticipated that 4000
hours of the 12-m Array time and 3000 hours of the Atacama Compact Array (ACA) time, also known as theMorita Array, will be available for successful proposals from Principal Investigators (PIs) in Cycle 6. Proposals
must be prepared and submitted using the ALMA Observing Tool (OT), which is available for download fromthe ALMA Science Portal (www.almascience.org). Proposals will be assessed by competitive peer review by asingle international review committee.
ALMA Cycle 6 proposal submission will open at 15:00 UT on Tuesday, 20 March 2018. The Cycle 6 proposal
submission deadline is 15:00 UT on Thursday, 19 April 2018. Table 1 summarises these and other importantmilestones for Cycle 6.
ALMA provides continuum and spectral-line capabilities for wavelengths from 0.32 mm to 3.6 mm, andangular resolutions from 0.018” to 3.4” on the 12-m Array. Cycle 6 will bring to ALMA several newobservational capabilities, including full circular polarization observations, lifting of some restrictions for
simultaneous observations with the 12-m Array and the ACA, Band 8 stand-alone ACA observations and anincrease of the Band 6 Intermediate Frequency (IF) bandwidth.
This Proposer’s Guide provides an overview of significant changes made in both the technical capabilities
and observing strategies for Cycle 6 (Section 1), an overview of the ALMA organisation (Section 2), the typesof proposals offered in Cycle 6 (Section 3), information on proposal planning (Section 4) and submission(Section 5), an overview of the offered technical capabilities (Appendix A), and guidelines for writing a
Technical Justification (TJ, Appendix B).
Table 1: The ALMA Cycle 6 timeline
Date

Milestone

20 March 2018 (15:00 UT)

Release of Cycle 6 Call for Proposals, Observing Tool & supporting documents andopening of the Archive for proposal submission

19 April 2018 (15:00 UT)

Proposal submission deadline

End of July 2018

Announcement of the outcome of the proposal review process

August - 6 September 2018

Submission of Phase 2 material

October 2018

Start of ALMA Cycle 6 Science Observations

September 2019

End of ALMA Cycle 64

1 What’s new in Cycle 6
This section summarises significant changes made in Cycle 6. Additionally, any changes, clarifications, orbugs that are discovered after the publication of this Proposer’s Guide will be documented in the
Knowledgebase Article:
What Cycle 6 proposal issues and clarifications should I be aware of before submitting my proposal?
All proposers should check this article regularly, especially just before submitting their proposals.

1.1

Technical and observing capabilities

The new observing modes that will be offered in Cycle 6 are listed below. Details of these observing modes
are given in Appendix A, with supplemental technical material given in the ALMA Cycle 6 TechnicalHandbook (hereafter, the Technical Handbook).
Circular polarization observations
Proposals will be accepted for Bands 3, 4, 5, 6 and 7 in all (including circular) polarization modes forcontinuum and spectral-line, single-field, on-axis, observations. The minimum detectable degree of circularpolarization, defined as three times the systematic calibration uncertainty, is currently 1.8% of the peak flux
for both continuum and spectral-line data.
Changes to simultaneous observations with the 12-m Array and the ACA
In Cycle 6, PIs can request simultaneous observations of any 12-m Array configuration (except those defined
as “long-baseline configurations”, see Section 4.2) with the 7-m Array (and, if required, the TP Array) in
which case all observations will have the same duration, namely that of the 12-m Array observation. For
simultaneous observations, the restrictions on allowed configuration combinations (except those involving
two 12-m Array configurations) and time multipliers specified in Section A.4 do not apply.
Band 8 stand-alone ACA
Band 8 observations will become a standard mode in Cycle 6 (see Section 4.2). Consequently, proposals will
be accepted for Band 8 stand-alone ACA observations.
Band 6 IF extension
The Band 6 IF bandwidth has been increased by 0.5 GHz to extend from 4.5 to 10 GHz. This will enable 12CO,
13
CO and C18O J=2-1 to be observed simultaneously with broader spectral windows.

1.2

Proposal format

In Cycle 6, the figure captions, tables and references included in the proposal Scientific Justification (SJ) mustuse a 12-point font (see Section 5.2.3).

1.3

Observing Tool features

The more notable changes for Cycle 6 include:

5

•
•
•
•

•

•
•
•
•

The minimum time on source (adding all the sources in a given Scheduling Block or SB) will be
the largest of 5 minutes or 50% of the total calibration time (amplitude and bandpass).
For calculation of the Executive Balance, the affiliation of a user, as well as his/her email, at thetime of a proposal’s last submission will be considered.
It is no longer possible to enter a user-defined bandwidth that exceeds the bandwidth of thespectral setup.
For sources distributed widely in the sky within one Science Goal (SG), the OT splits the SG into
different “clusters”, each grouping all sources within a radius of 10 degrees (see Section A.8.1).
In Cycle 6, for SGs that request “long-baseline configurations” (see Section 4.2 for definition) thegrouping of sources into clusters will consider only sources within a radius of 1 degree (seeSection A.8.1). For all other baselines, the grouping remains unchanged.
The LSRK to barycentric correction now works properly for all velocity definitions. This may
result in projects from previous cycles not validating. If so, the spectral setup should be
modified.
There is no longer a text box associated with the time-constraint interface. The box on the TJ
node should be used instead.
FITS files in Galactic coordinates are now handled correctly.
Source coordinates in decimal degrees input in an ASCII format will now be recognised as
Galactic.
The OT will issue a validation error if a given SG exceeds the instantaneous maximum data rateof 70 MB/s.

All new features are described in more detail in the OT documentation.

2 ALMA overview
2.1

The ALMA partnership

ALMA, an international astronomy facility, is a partnership of the European Organisation for Astronomical
Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National
Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA construction
and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy
Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the
National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. JAO provides the unified
leadership and management of the construction, commissioning and operation of ALMA.

2.2

The ALMA telescope

ALMA contains 66 high-precision antennas. Fifty of these antennas are 12 metre dishes in the 12-m Array,used for sensitive, high-resolution imaging. The remaining sixteen antennas make up the ACA, used toenhance wide-field imaging: twelve of those are closely spaced 7 metre antennas (7-m Array), and four are
12 metre antennas for single-dish observations (Total Power, or TP, Array). The wavelengths currently
covered by ALMA range from 0.32 mm to 3.6 mm (frequency coverage of 84 GHz to 950 GHz).
6

The Array is located on the Chajnantor plateau (referred to as the Array Operations Site, AOS) of the Chilean
Andes at latitude = −23.029°, longitude = −67.755° and an altitude of 5000 m. The site offers the
exceptionally dry and clear sky conditions required to operate at millimetre and submillimetre wavelengths.
This site is connected via Gigabit fibre links to the Operation Support Facility (OSF), located at an altitude of2900 m, at 40 km from the town of San Pedro de Atacama. Science operations are conducted from the OSF
and coordinated from the JAO Santiago Central Office (SCO).
The Technical Handbook contains a detailed description of the ALMA technical characteristics.

2.3

The Joint ALMA Observatory and the ALMA Regional Centres

The JAO is responsible for the overall leadership and management of ALMA operations in Chile. The JAO
solicits proposals to observe with ALMA through Calls for Proposals and organises the peer review of the
proposals by science experts. In addition, the JAO schedules all science observations and places the data inthe electronically accessible archive.
The three Executives maintain the ALMA Regional Centres (ARCs) within their respective region. The ARCs
provide the interface between the ALMA Observatory and its user communities. The ARCs are responsible
for user support, mainly in the areas of proposal preparation, observation preparation, acquisition of data
through the Archive, data reduction, data analysis, data delivery, face-to-face visitor support and workshops,
tutorials, and schools. Each ARC operates an archive that is a mirror of the SCO Archive. Browsing and data
mining are done through the ARC mirror archives.
The East Asian ARC (EA ARC) is based at the National Astronomical Observatory of Japan (NAOJ)
headquarters in Tokyo. It is operated in collaboration with Academia Sinica Institute of Astronomy andAstrophysics (ASIAA) in Taiwan and Korea Astronomy and Space Science Institute (KASI) in Korea andsupports the astronomical communities of Japan, Taiwan 1 and Republic of Korea.
European researchers are supported by the European ARC (EU ARC), which is organised as a coordinatednetwork of scientific support nodes distributed across Europe. The EU ARC is located at ESO Headquarters in
Garching bei München (Germany), where many of the ARC activities take place. Face-to-face support andadditional services are provided by seven regional nodes and one centre of expertise. The regional nodes are
currently: Bonn-Cologne (Germany), Bologna (Italy), Onsala (Sweden), IRAM, Grenoble (France), Allegro,
Leiden (The Netherlands), Manchester (United Kingdom) and Ondřejov (Czech Republic). The Portuguese
ALMA Centre of Expertise (PACE) is located in Lisbon (Portugal).
The North American ARC (NA ARC) is contained within the North American ALMA Science Center (NAASC),
based at NRAO headquarters in Charlottesville, VA, USA. It is operated in collaboration with the National
Research Council of Canada (Canada) and Academia Sinica Institute of Astronomy and Astrophysics (Taiwan),and supports the astronomical communities of North America and Taiwan1.

1

Support of the Taiwanese astronomical community is shared by the EA and NA ARCs.

7

2.4

The ALMA Science Portal

The ALMA Science Portal (SP), accessible at http://www.almascience.org, is the primary access point to
ALMA for science users. It provides a gateway to all ALMA resources, documents and tools relevant to users
for proposal preparation, proposal assessment, project tracking, project data access and data retrieval, as
well as access to the ALMA Helpdesk.
From the Science Portal, anyone can:
•
•
•
•
•

Register as an ALMA user.
Access ALMA user documentation and software tools, including the ALMA Sensitivity Calculator,
observing simulators, and the ALMA spectral-line database (Splatalogue).
Download the OT.
Access Helpdesk “Knowledgebase” articles, which provide answers to common questions.
Access non-proprietary data from the ALMA Archive.

In addition, registered users may:
•

•
•
•
•

Manage their user profile. For PIs, this includes the option to receive automatic email notificationsof the progress of their observations, to enable access to proprietary data to other ALMA users or todelegate the right to submit the Phase 2 material to another selected ALMA user.
Access SnooPI, the tool for PIs, co-PIs, co-Investigators (co-Is) and any other user designated by thePIs, to monitor the status of their scheduled observing projects.
Submit Helpdesk tickets.
Trigger Target of Opportunity (ToO) observations.
Access their proprietary data through the ALMA Archive.

The Science Portal also includes links to the ARCs webpages from which users can access regional
information and specific services of each ARC, such as visitor and student programmes, schools, workshops,
and outreach materials and activities.
Users must update their ALMA user profile, rather than registering multiple accounts, whenever there is achange in their personal details such as a new email address or a change of affiliation (see Section 2.1 of the
ALMA Users’ Policies).

2.5

ALMA proposal eligibility

Users of any nationality or affiliation may submit an ALMA proposal. All proposals are evaluated on the basisof scientific merit and technical feasibility by a panel-based proposal review system.
Each proposal must have a PI who is the official contact between ALMA and the proposing team for all
correspondence related to the proposal. Large Programmes and mm-VLBI Proposals may designate co-PIs,
who will share the overall responsibility in conducting the proposed science. Regardless of the inclusion of
co-PIs, the PI has the responsibility for preparation and approval of the Phase 2 material, has proprietary
access to the ALMA data during the proprietary period and is in charge of the delivery of the data productsin the case of Large Programmes, in accordance with the ALMA Users’ Policies. Any other individuals who
are actively involved in any proposal may be designated as co-Is. There is no limit to the number of co-PIs or
co-Is who may appear on a proposal.
8

The requested observing time will be split among the regions (North America, Europe, East Asia, and Chile)
based on the proportionality of the regional affiliation of the PI and co-PIs (Section 5.5.3).
Additional rules apply for qualification to use the Chilean share of the time and they are described at
http://www.das.uchile.cl/das_alma_crc.html.
ALMA Users’ Policies prohibit multiple submissions of the same proposal using different regional affiliations.
If such proposals are detected, only the first submitted version will be considered by the ALMA review
panels.

3 Proposal types
3.1

Regular Proposals

Regular Proposals refer to observations that can be fully specified by the regular proposal submission
deadline and whose estimated execution time does not exceed 50 hours on the 12-m Array or 150 hours on
the ACA in stand-alone mode. Regular Proposals may include standard or non-standard modes and may
involve time-critical, multiple-epoch observations, and the monitoring of a target over a fixed time interval.
As shown in Figure 1 (left panel), the requested time of the majority of Cycle 5 proposals is between two andten hours of 12-m Array time. However, the success rate of proposals was roughly constant up to at least 30
hours of requested 12-m Array time (see Figure 1, right panel). ALMA continues to encourage thecommunity to submit Regular Proposals that request over 10 hours of 12-m Array time.
No restrictions are imposed on the size of the time window specified by PIs for time-critical observations.
The scheduling feasibility of any proposal will depend on the total number of constraints that are imposed(see Section 4.3). Importantly, any time constraint, as with any other type of observational constraint, mustbe scientifically and technically justified.

Figure 1: (Left) Number of proposals submitted as a function of the 12-m Array execution time in Cycle 5. (Right) The
fraction of proposals (with 1σ confidence intervals) that are assigned priority Grade A or B as a function of theestimated 12-m Array time.

9

3.2

Target of Opportunity Proposals

Target of Opportunity (ToO) Proposals should be submitted for observations that can be anticipated but
whose targets and/or time of observation are not known in advance. Like Regular Proposals, these proposals
must be submitted by the Cycle 6 proposal deadline and may include standard or non-standard modes. As
for all other types of proposals, observing modes and sensitivity requests must be specified at the time ofsubmission. In contrast, the target list may be specified at the moment of triggering the proposal. For eachtriggered SB the proposal should specify the number of triggers needed, what the trigger event will be, andthe necessary reaction time for scheduling the observation after it is triggered. Regular Proposals wrongly
submitted by the PI as ToO Proposals may be rejected on technical grounds.
The JAO will give priority to observing ToO Proposals during the time period requested by the PI at the
moment of triggering provided the appropriate scheduling conditions (mainly weather and antennaconfiguration, see Section 4.3 ) are met and the observations do not conflict with critical engineering anddevelopment activities or critical observations with a higher grade. ToO observations triggered while the 12m Array is in one of the most extended configurations are possible but may be subject to longer reaction
times. For requests of reaction times under 24 hours, the Observatory recommends that PIs give notice as
early as possible about target coordinates or redshift for preparation of the Phase 2 SBs. PIs will trigger
observations from accepted ToO Proposals through the Project Trigger Submission Page available at the
ALMA Helpdesk (further instructions on how to trigger a project are available at the Science Portal). Further
communication of the Observatory with the PI to clarify any necessary issues for the ToO observations willproceed via the Helpdesk ticket opened upon trigger receipt.
For ToO observations that require follow up/subsequent observations based on the outcome of the initialobservation, the PIs have the possibility to request the release of the raw data to enable a prompt analysis.
Requests for these raw data should be submitted through the ALMA Helpdesk. In Cycle 6, the proprietary
period for these observations will start when the quality assured data products are delivered to the PI, as forany other observation (Section 6.3).

3.3

Large Programmes

Large Programmes are proposals with an estimated execution time of greater than 50 hours on the 12-m
Array (with or without accompanying ACA time) or 150 hours on the ACA in stand-alone mode. Large
Programmes must include only standard modes (as defined in Section 4.2) and should not involve timecritical or ToO observations.
A Large Programme proposal should address strategic scientific issues that will lead to a major advance or
breakthrough in the field, be a coherent science project, not reproducible by a combination of Regular
Proposals, lead to high level archival data products, and contain a solid management plan ensuring anefficient utilisation of the data, including analysis and organisation of the efforts. Consequently, the proposal
team for a Large Programme should not in parallel submit their Large Programme as one or more Regular
Proposals, in which case the Regular Proposals will not be considered (further details on this policy areavailable at the KB article “Are there policies specific to Large Programs?”).
The programme teams are expected to deliver their proposed data products and documentation describing
the data products to ALMA within one year of the final delivery of calibrated data. The data products and10

documents will be made available to the community at large. ALMA will inform the PIs of approved Large
Programmes about the standards for product naming, product metadata and product quality.
A maximum of 15% of the time available for science observations will be dedicated to the execution of Large
Programmes, corresponding to 600 hours of 12-m Array time and 450 hours of stand-alone ACA time
(Section 4.1). To optimise the success in completing the observations within Cycle 6, the following
scheduling constraints will be imposed when selecting Large Programmes: (1) the time allocated to Large
Programmes shall not exceed 33% of the available time for a given Local Sidereal Time (LST) range on
antenna configurations with baselines longer than 12 km (configurations C43-9 and C43-10, see Section
4.3.3); and (2) the time allocated to Large Programmes shall not exceed 50% of the available time for a given
LST range on configurations with baselines shorter than 12 km (ACA and C43-1 to C43-8).

3.4

mm-VLBI Proposals

ALMA VLBI Proposals in Bands 3 and 6 are made in concert with the following VLBI networks: the Global
Millimetre VLBI Array (GMVA) at 3 mm and the Event Horizon Telescope Consortium (EHTC) network at 1.3
mm. For 3 mm VLBI observations, PIs must have submitted a proposal to the GMVA network by 1 February
2018 in addition to their ALMA VLBI proposal (see 3 mm VLBI announcement).
ALMA-specific VLBI considerations are given in Section A.12 of this document. Further details on submitting
3 mm VLBI Proposals to the GMVA are available from the GMVA website. Further details on submitting 1
mm VLBI Proposals to EHTC are available from the EHTC website.
Proposals should include a quantitative justification as to why ALMA is essential for the goals of the project.
VLBI observations cannot be included in Large Programmes and DDT Proposals.
VLBI observations that include ALMA will likely occur in March/April 2019 while ALMA is in a compact
antenna configuration (Section 4.3.3), with up to thirty-nine 12 m antennas in the phased array.
Given that the outcome of VLBI Cycle 5 proposals, scheduled in April 2018, is unlikely to be known before
the ALMA Cycle 6 proposal deadline, PIs of such proposals may wish to resubmit their proposals in Cycle 6 incase the Cycle 5 observations are unsuccessful. No resubmission to the GMVA network is needed in suchcases. Further details on handling of resubmitted proposals are available in Section 4.4.2.

3.5

Director Discretionary Time Proposals

Director Discretionary Time (DDT) Proposals may be submitted at any time during Cycle 6 for execution
during this cycle. To qualify for DDT usage, proposals must fulfil the conditions specified at the Science
Portal. Capabilities, time tolerance restriction, and science assessment will be based on the same criteria as
for Regular and ToO Proposals. DDT Proposals will be considered for approval by the ALMA Director basedon the advice of a Standing Review Committee, with members from the JAO and the four regions, appointed
by the Executive Directors and the ALMA Director. In exceptional cases, the ALMA Director may approve
DDT Proposals that would benefit from a very rapid response, and inform the Standing Committee andscience operations team of this decision within 24 hours. Further DDT policies are described in the ALMA
Users’ Policies.

11

4 Proposal planning
4.1

Time available in Cycle 6

Cycle 6 will have a duration of 12 months, starting in 2018 October and finishing in 2019 September.
It is anticipated that 4000 hours of the 12-m Array and 3000 hours of the ACA will be available for successfulproposals of PI programmes and DDT Proposals, including Cycle 5 grade A proposals that are carried over.
Up to 20% of the available time can be allocated to non-standard observing modes, which are listed in Table
2. Large Programmes, VLBI 2 and DDT Proposals are limited to a maximum of 15%, 5% and 5% (respectively)of the available time (Sections 3.3, 3.4 and 3.5).

4.2

Summary of capabilities offered in Cycle 6

The Cycle 6 capabilities are described in Appendix A. In summary they are:Number of antennas• At least forty-three (43) antennas in the 12-m Array.

• At least ten (10) 7 m antennas (for short baselines) and three (3) 12 m antennas (for making singledish maps) in the ACA.

Receiver bands• Receiver Bands 3, 4, 5, 6, 7, 8, 9, and 10 (wavelengths of about 3.0, 2.0, 1.6, 1.3, 0.85, 0.65, 0.45, and0.35 mm, respectively).

12-m Array Configurations• Maximum baselines between 0.16 km and 16 km depending on array configuration and subject tothe following restrictions:o The maximum possible baseline for Bands 8, 9 and 10 is 3.6 km.
o The maximum possible baseline for Band 7 is 8.5 km.
o The maximum possible baseline for Bands 3, 4, 5 and 6 is 16 km.
Configurations with maximum baselines equal or longer than 3.6 km (C43-7 to C43-10) are considered“long-baseline configurations”. Observations in these configurations include more frequent calibrationcompared to more compact configurations to ensure the quality of the observations. Files containing
representative antenna configurations for the 12-m and 7-m Arrays suitable for Common Astronomy
Software Applications (CASA) simulations are available from the ALMA Science portal.
Spectral-line, continuum, and mosaic observations• Spectral-line and continuum observations with the 12-m Array and the 7-m Array in all bands.
• Single-field interferometry (all bands) and mosaics (Bands 3 to 9) with the 12-m Array and the 7-m
Array.

• Single-dish spectral-line observations in Bands 3 to 8.

Note that the 5% of time allocated to VLBI Proposals is included in the 20% of the time allocated to non-standard
modes (Section 5.2).
2

12

Polarization• Single pointing, on axis, full linear and circular polarization capabilities for continuum and full
spectral resolution observations in Bands 3, 4, 5, 6 and 7 on the 12-m Array. The field of view of
linear and circular polarization observations is limited to the inner one-third and the inner one-tenthof the primary beam, respectively.
Cycle 6 observing modes are classified as standard or non-standard. Standard modes have been wellcharacterised and the observations can be calibrated with the ALMA data reduction pipeline. Non-standard
modes, listed in Table 2, are not as well characterised and may require additional Observatory resources tocalibrate, image and deliver ALMA data products. Up to 20% of the Cycle 6 observing time will be allocatedto proposals requesting non-standard modes.
Table 2: List of non-standard modes
Bands 9 and 10 observations
Band 7 observations with maximum baselines > 5 km
All polarization observations
Spectral scans
Bandwidth switching projects (having less than 937.5 MHz aggregate bandwidths over all
spectral windows)
Solar observations (Bands 3 and 6)
VLBI observations
User-specified calibrations
Astrometric observations

Stand-alone ACA observations are available for standard modes only.

4.3

Scheduling considerations

Apart from time-constrained observations, various aspects of a proposed observation such as weather
conditions or requested angular resolution and Largest Angular Structure (LAS) may affect when an
observation is scheduled. This section describes the most important scheduling considerations thatinvestigators should be aware of when preparing their ALMA proposal.

4.3.1 Weather
Chajnantor is one of the best sites in the world for ground-based observations at submillimetre wavelengths(Evans et al 2002, ALMA Memo No. 471, available from the ALMA Memo Series). The opacity (primarily
determined by the amount of Precipitable Water Vapour – PWV) and the phase stability of the atmosphere
are the two primary factors that dictate when ALMA can observe at certain frequencies, in particular in thehigher-frequency bands and at frequencies near water absorption lines. Both transmission and phasestability follow a yearly cycle (late southern winter is best – see Figures 2 and 4 of Memo 471) and a diurnal
cycle (late night and early morning are best – see Figures 3 and 5 of Memo 471). In addition to thetransmission and phase stability criteria, the low wind speeds that typically occur during night and earlymorning provide optimum observing conditions.

13

Figure 2 shows the PWV measurements per month, illustrating the yearly cycle. The best months for highfrequency observations are from May to November. Figure 3 shows the percentage of time when the PWV isbelow the observing thresholds adopted for the various ALMA bands. Such time percentage is shown permonth and separately for day and night to highlight the daily and monthly variations. For a given time of the
day and a given month, the PWV measurements still show a large scatter, due to the differences in weather
from year to year. During parts of the year, such as the Altiplanic winter 3 season (January-March), it may bedifficult to carry out submillimetre observations. For this reason, an extended maintenance and upgrade
period is scheduled each February, during which no science observations are scheduled.

Figure 2: Fraction of time that the PWV falls below a given value along the year. The percentages shown indicate thefraction of time that the PWV is under the PWV value indicated on the y-axis. For example, in March 75% of the PWV
measurements are under 4.1 mm, and in June 75% of the PWV measurements fall below 1.8 mm. The data wereobtained with the APEX weather station between 2007 and 2017. The horizontal dashed lines show the observing
thresholds adopted for the various ALMA bands for an elevation of 60 degrees.

During southern summer, the high-pressure system over the Pacific Ocean weakens and moves southwards, allowing
warm humid air from the Amazons to flow over the Andes into northern Chile, causing rain and occasionally snow tofall on the usually dry Altiplano: this phenomenon is known as Altiplanic winter.

3

14

Figure 3: The percentage of time when the PWV is below the observing thresholds adopted for the various ALMA bands
for night-time (green) and afternoon (yellow) and for an elevation of 60 degrees. The horizontal line within the box
indicates the median. Boundaries of the box indicate the 25th- and 75th- percentile, and the whiskers indicate thehighest and lowest values of the results. The data were obtained with the APEX weather station between 2007 and2017.

The Observatory will schedule the observations during appropriate weather conditions and to ensure gooddata quality. In particular, this implies that high frequency projects will get priority over other lower
frequency projects when the weather conditions are appropriate for the former, thus increasing theirprobability of execution.

4.3.2 Angular resolution
PIs can enter a range of angular resolutions for a given SG in the OT. An extended range of angularresolutions, spanning more than one configuration, will lead to an increased chance of having the SBs
corresponding to a given SG observed, especially for SBs with an intrinsically low probability of execution
due to, for example, weather or time constraints. The range should be justified in the proposal and be
scientifically meaningful (Section 5.2).
In practice, the OT will assign to a given SB any number of configurations that fulfil the angular resolution
range requested by the PI. For scheduling feasibility and Quality Assurance (QA) purposes, the following will
also be taken into account:15

•

If the PI selects a single value for the angular resolution or a range narrower than 20% around its
centre value, a range of ±20% around the single or centre value specified will be enforced.

•

If the requested range (after applying the previous rule) does not include the resolution of at least
one of the nominal configurations, the range will be extended to include the resolution of theclosest nominal configuration.

•

If the requested range includes both “long-baseline configurations” and more compact
configurations, only the latter subset will be considered.

The final range of angular resolutions (i.e. after all the above factors have been taken into account) that theObservatory will use, and the corresponding set of configurations, are displayed in the Phase 2 SBs in the OT
so that they can be reviewed by PIs.
PIs aiming to obtain a specific surface brightness may enter their sensitivity request in temperature units. In
this case, if a range of acceptable resolutions is specified by the PI, the time estimate will be determined by
the time needed to achieve the surface brightness sensitivity requested at the resolution of the mostextended configuration fitting the provided range (i.e. finest resolution). ALMA QA processes are defined interms of resolution and flux density sensitivity, so the actual surface brightness sensitivity delivered will
depend on the resolution achieved by the observations (see Chapter 11 of the Technical Handbook for moredetails). This implies that a temperature sensitivity worse than requested could be obtained if the resolution
achieved in the delivered images is still within the requested range but finer than that of the most extended
configuration assigned to that SB.

4.3.3 Configuration schedule for the 12-m Array
During Cycle 6, it is anticipated that the 12-m Array will be reconfigured fourteen times. At the end of eachof these reconfigurations, the Array is expected to have imaging properties similar to one of the ten“representative” configurations that are used to characterise the advertised Cycle 6 imaging capabilities andestimate the observing times (denoted as C43-x, with x=1 for the most compact configuration and x=10 for
the most extended; see Section A.2 and Chapter 7 of the Technical Handbook for details). The planned 12-m
Array configuration schedule for Cycle 6 is given in Table 3. The overall schedule may also be modified
depending on the results of the proposal review process and the proposal pressure in the different
configurations. Changes to the configuration schedule will be made available at the Science Portal. On
average, there will be a new configuration every three weeks. As mentioned in Section 4.3.1, observations
will not be scheduled in February due to the bad weather conditions during the Altiplanic winter.
The first column of Table 3 gives the planned start date for each configuration. These dates may be subject
to change due to weather conditions. The second column gives the 12-m Array configuration, and the thirdcolumn lists the longest baseline for the configuration (see Table A-1). The fourth column lists the LST ranges
when the observing conditions are most stable, which is approximately two hours after sunset to 4 hours
after sunrise (Section 4.3.1). The effective observing time available per configuration for executing PI
projects (excluding time spent on observatory calibration, maintenance, reconfigurations, and otheractivities – see Section 4.3) is shown in Figure 4.

16

Table 3: Planned 12-m Array Configuration Schedule for Cycle 6
Start date

Configuration

Longest baseline

LST for best observing conditions

2018 October 1

C43-6

2.5 km~ 22h – 10h2018 October 15

C43-5

1.4 km~ 0h – 12h2018 November 25

C43-4

0.78 km~ 2h – 14h2018 December 15

C43-3

0.50 km~ 4h – 15h2019 January 5

C43-2

0.31 km2019 January 20

C43-1

0.16 km2019 February 1-28

~ 5h – 16h~ 6h – 17h

No observations due to February shutdown2019 March 1

C43-1

0.16 km2019 March 15

C43-2

0.31 km2019 April 1

C43-3

0.50 km2019 April 15

C43-4

0.78 km2019 May 1~ 8h – 21h~ 8h – 22h~ 9h – 23h~ 10h – 0h

No observations due to major antenna relocation

2019 June 1

C43-1016.2 km~ 13h – 3h2019 June 20

C43-9

13.9 km~ 14h – 5h2019 July 10

C43-8

8.5 km~ 16h – 6h2019 August 1

C43-7

3.6 km~ 18h – 8h2019 September 5

C43-6

2.5 km~ 20h – 9h

Notes for Table 3:
1. Configuration properties are given in Section A.2

Given the anticipated configuration schedule and taking into account the weather constraints, the following
considerations apply:•

Band 9 and 10 observations will be scheduled during the LST ranges given in the fourth column ofTable 3, corresponding to more stable weather conditions (Section 4.3.1). The amount of time withstable atmospheric conditions suitable for Bands 7 and 8 observations outside of those LST ranges islimited (see Figures 2 and 3). To maximise the completion of high frequency observations, suchprojects are given priority in the observing queue when the weather conditions are suitable (Section
4.3.1).
17

•High frequency projects (Bands 7, 8, 9, and 10) and Band 5 observations near the atmosphericabsorption feature at 183 GHz are not recommended around the Altiplanic winter (especiallyDecember-March) at any LST.

•

The probability that an observation be scheduled depends on the over-subscription for a given LST
and configuration besides the required weather conditions. In particular in Cycle 5, projects
requesting configurations C43-8, 9, or 10 had a higher success rate than those requesting otherconfigurations. Also, stand-alone ACA observations have a high probability of being scheduled,especially at LST between 20 h and 14 h.

• Projects that have imaging requirements (constraining the necessary configuration) and other time
constraints (e.g. due to coordination with other observatories) that do not coincide cannot bescheduled.
The extended, long-baseline, configurations for Cycle 6 will occur from June to August. Long periods suitablefor high frequency observing are expected from August to November. In Cycle 7 the array configuration
schedule will likely complement this plan.

Figure 4: Effective observing time available per configuration for executing PI projects. As an example, up to 10 hours
may be allocated to Large Programmes in configuration C43-2 at LST = 10 h. The total number of hours excludes timespent on observatory calibration, maintenance, reconfigurations, and other activities. The fraction of that time
available for Large Programmes (pink) and high frequency observations (green and dark blue) is also indicated. The
configuration schedule and, consequently, the total number of hours available per configuration may change as a resultof proposal pressure (Section 4.3.3). The data files containing these histograms are available here.

18

4.3.4 Observing pressure
Figure 5 shows the LST distribution of Cycle 5 submitted proposals and of those awarded grades A-C byconfiguration and array type. While some LST ranges such as 2-6 h or 12-19 h show over-subscription inseveral configurations, the degree of over-subscription differs significantly for different configurations. In
general, proposals in less subscribed LST ranges will have a higher probability of execution.
The range of angular resolutions provided by PIs (Section 4.3.2) will have a direct impact on the observingpressure per configuration. Proposals that specify a broad range of acceptable angular resolutions (i.e.,several acceptable configurations) increase their likelihood of being scheduled and executed. However, PIs
should only request the range of angular resolutions that is acceptable for their science goals, as this will be
evaluated during the proposal review process.

Figure 5: Distribution of estimated execution time in Cycle 5 proposals for all submitted proposals (gray) andproposals assigned Grade A, B, or C (blue). The figure does not include the unfinished Cycle 4 Grade A proposals
carried over to Cycle 5.

4.4

Duplicate observations and resubmissions

4.4.1 Checking for duplications
To ensure the most efficient use of ALMA, duplicate observations of the same location on the sky withsimilar observing parameters (frequency, angular resolution, coverage, and sensitivity) are not permitted
unless scientifically justified. Archival data should be used whenever possible to accomplish the science19

goals of a proposed investigation. Observations are considered duplicates if the conditions indicated inAppendix A of the Users’ Policies are met.
PIs are responsible for checking their proposed observations against the Archive and the list of Cycles 4 and
5 Grade A programmes provided by ALMA to avoid duplicate observations. PIs will not be penalised for
proposing duplications of previous cycle observations if they had no way to know about them, using theresources listed above, by the release of the Call for Proposals. More information on checking for
duplications is available at the Science Portal.
The proposal cover sheet contains a section where PIs can justify proposed duplicate observations. PIs arealso advised to justify their proposed observations in cases where they are similar to previously executed or
accepted programmes but are not formal duplicates. This will help the reviewers understand why new
observations are requested. The ALMA Review Panels (ARPs) will determine if the justification for a
duplicate observation is sufficient.
Examples of duplicate observations that may be approved include:• Synoptic observations of time-variable phenomena.
• A large-area survey where cutting out a smaller area to avoid overlap with a previous observation
will make the observation inefficient and increase the overall execution time.
• Spectral scan surveys where excluding a frequency range covered by a previous observation will
make the observation inefficient and increase the overall execution time.

4.4.2 Resubmission of an unfinished proposal
Proposal teams that submit a Cycle 6 proposal to observe some or all SGs of a currently active but unfinishedproject will have the relevant SGs identified as a “resubmission” by ALMA. A SG is deemed a “resubmission”
if it constitutes a duplication of an active SG following the rules specified in Appendix A of the Users’ Policies
and the PI of the relevant Cycle 5 project is listed as a PI, co-PI or co-I of the corresponding Cycle 6 proposalor the Cycle 6 PI is listed as an investigator on the Cycle 5 proposal.
For such resubmissions, the relevant portion of the Cycle 6 proposal will be cancelled if the observations are
successfully completed in Cycle 5. Observations started in a previous cycle and accepted as a resubmission in
Cycle 6 will continue to be observed with the setup of the previous cycle.
A scientific justification must be provided if the proposers request one or more additional epochs ofobservations in Cycle 6 even if the Cycle 5 observations are completed. The APRC will decide if suchresubmissions are accepted.

4.5

Estimated observing time

Proposal requests are cast in terms of Science Goals, each containing a complete observational setup(desired sensitivity, range of angular resolutions and LAS, frequency band, spectral windows and spectral
resolutions) to be obtained for one or more sources. The OT Quickstart Guide and the OT User Manual
provide extensive details and guidance for preparing the SGs. Experienced users who wish to understandhow ALMA observations are set up are referred to Chapter 8 of the Technical Handbook.
The observational setup of a given SG is used to estimate a total observing time for that SG (except for Solaror VLBI observations or when overridden by the PI - see Appendix B). This observing time is the sum of the20required time-on-source for all science targets, time for all calibrations including overheads, and the time forany additional array configurations needed to meet the specified LAS. The estimated observing time for the
proposal is the sum of the times for all SGs. The actual observing time to reach a given sensitivity, resolution
and LAS will depend on the prevailing conditions when the project is observed, the number of antennas
available, and the actual array configuration.
The estimated time-on-source is calculated with the ALMA Sensitivity Calculator (ASC), available within the
OT or as a stand-alone web application on the Science Portal. The parameters that affect these time
estimates include requested sensitivity, source declination, observing frequency, spectral bandwidth,
number of antennas, angular resolution (if the sensitivity is specified in temperature units 4) and default
weather conditions. A description of the ALMA Sensitivity Calculator is given in Chapter 9 of the TechnicalHandbook.
The estimated time for calibrations and overheads is calculated by the OT and will depend on the frequency,
configuration and type of observation (e.g. full polarization requires additional calibrations). Proposals
requesting the suppression of some or all calibrations will be flagged as non-standard and may be deemed
technically unfeasible if the request is not properly justified in the proposal (see Section B.4 for details).
For each SG one or more SBs are generated during Phase 2 depending on the distribution of sources in thesky and the number of configurations needed (Sections A.8.1 and A.4, respectively). Each SB contains all thecommands needed to perform the observations and a complete set of calibrations. The minimum durationof the SB is constrained by a minimum time-on-source of 5 minutes for the sum of all the sources in the SB
or 50% of the total calibration time (see Section 5.3.5.3 of the OT User Manual). For SGs that require a
combination of arrays but have short time-on-source that is increased to the 5-minute minimum by the OT,
the time multipliers given in Table A-2 may not be preserved (see Section A.4). The maximum duration of
the SB is around 2 hours (determined by a maximum time-on-source of 50 minutes) and each SB will be rerun as many times as needed to achieve the requested signal-to-noise (S/N) ratio. Consecutive executions ofa given SB (if needed) are favoured during scheduling to maximise uv-coverage. However, if uv-coverage isfundamental for the scientific goals of a proposal, PIs should specify this request as a time constraint, and, if
necessary, override the OT time estimate with the time needed to achieve such uv-coverage (see Section B.2
for details). Data from each SB will be processed, assessed, and delivered independently.
The final factor in the time estimate is the time for any additional configurations needed to supplement theconfigurations that best match the requested range of angular resolutions to also reach the specified LAS(see Table A-1 in Appendix A). The LAS is compared to the “Maximum Recoverable Scale” (MRS) of theconfigurations that best match the requested range of angular resolutions (MRS are also listed in Table A-1).
If the LAS exceeds the MRS of all matching configurations, then additional configurations, if allowed (Section
A.4), are added with a time estimated using the multipliers given in Table A-2. If the array combinations are
not allowed (Section A.4), the OT will give a validation error. If the LAS can be achieved with one or more of
the best-matching configurations, the remaining configurations meeting the angular resolution but not the
LAS request will not be considered.

Since Cycle 5, the time estimate adopts the configuration that fulfils the finest angular resolution requested if thesensitivity is specified in temperature units (Section 4.3.3).

4

21

The PI may include additional SGs for array combinations not allowed in a single SG, but each SG must be
separately justified and have its own performance specifications (sensitivity, range of angular resolutions,and LAS).
Observations that require only the ACA are selected by checking a specific box at the OT interface. Whencalculating the time required for ACA, the OT uses the TP Array time if this array is required (based on LAS)
or otherwise the 7-m Array time; i.e., it is not the sum of the 7-m and TP Array time. In case of simultaneous
observations in the 12-m and 7-m Arrays, the estimated time for the 7-m Array will set equal to that of the
12-m Array.
The results of all the time estimates are reported in the OT per SG by clicking “Time Estimate” in the“Desired performance” box. A summary of the time estimate of each SG can be viewed by clicking the “TimeSummary” button on the OT toolbar. The times for the 12-m Array and ACA and total time are tabulated
separately on the proposal coversheet.

4.6

Supporting tools and documentation

4.6.1 The Observing Tool documentation
The ALMA OT, a Java-based application that resides and runs on the user’s computer, is used to prepare andsubmit observing proposals (Phase 1) as well as to prepare the observations for execution on the telescope(Phase 2) if the proposal is accepted. Oracle has scheduled an update of Java 8 for mid April and users areadvised to wait until after the proposal deadline (19 April 2018) before installing this.
The OT documentation suite, which provides all the basic information required to complete the proposal
preparation and submission, includes:•

The OT Phase 1 Quickstart Guide: A guide to proposal preparation for the novice ALMA OT user. It
provides an overview of the necessary steps to create an ALMA observing proposal.

•

The OT Video Tutorials: A visual demonstration of proposal preparation and submission with the OT.

•The OT User Manual: A manual intended for all ALMA users, from novices to experienced users. It
provides comprehensive information about how to create valid Phase 1 proposals and Phase 2
programmes for observing astronomical objects. It is also included as part of the “Help”
documentation within the OT itself.

•

The OT Reference Manual: A manual providing a concise explanation for all the fields and menu
items in the OT. It is also included as part of the “Help” documentation within the OT itself.

•

The OT trouble-shooting page: A list of the OT installation requirements and workarounds forcommon installation problems.

• The known OT issues page: A list of currently known bugs, their status and possible workarounds.
This page may be updated during the proposal submission period and should be checked first if
problems are experienced with the OT.

22

4.6.2 Additional proposal preparation tools
Two tools are available to help users produce simulated images of ALMA observations of simple or userprovided science targets. A guide for simulating ALMA observations with either tool is available at the CASA
guides website.
The first simulation tool is integrated into CASA, the offline data reduction and analysis tool for ALMA data.
CASA includes the tasks “simobserve” and “simanalyze”, which generate simulated ALMA data and makeimages from the simulations. An additional CASA task, “simalma”, simplifies the process of combining datafrom multiple arrays. These CASA tools require configuration files that specify the layout of ALMA antennas.
Files for representative Cycle 6 configurations are available at the Science Portal. Additional information on
CASA, including hardware requirements and download instructions, is available at the CASA website.
The second simulation tool is the ALMA Observation Support Tool (OST). The OST uses a simplified webinterface to help users generate ALMA simulations. Users submit jobs to the OST and are notified by email
when the simulations are completed. The OST documentation is available at the OST website.
Splatalogue is a database containing frequencies of atomic and molecular transitions emitting in the radio
through submillimetre wavelength range. This database is used by the ALMA OT for spectral-line selection.
More information is available in the Splatalogue QuickStart Guide on the Science Portal.
The atmospheric transmission at the ALMA site can be investigated with the Atmosphere Model tool, whichallows the user to model the atmospheric transmission as a function of frequency and amount of PWV. The
output is a plot of the transmission fraction as a function of frequency. Up to six different water vapour
levels can be selected.

4.6.3 The ALMA Regional Centre Guides
The ARC Guides contain user support details specific to each ALMA regional partner. They are:•

The East-Asian ARC Guide•

The European ARC Guide•

The North American ARC Guide

4.6.4 Supplemental documentation
The following documents supplement this Proposer’s Guide for the preparation of Cycle 6 proposals, foreither the novice or advanced users. All documents can be accessed via the ALMA Science Portal.
The Proposing Guidance link from the science portal summarises the steps involved in the preparation andsubmission of an ALMA observing proposal. It is designed to help users to find the relevant documents andsources of additional information in each step easily.
Observing with ALMA: A Primer is a brief introduction to ALMA observing, to submillimetre terminology,
and to interferometric techniques, that should prove useful for investigators who are new to radio
astronomy. Several example science projects illustrating the Cycle 6 capabilities are also provided.

23

The ALMA Users’ Policies document contains a complete description of the applicable users’ policies. The
long-term core policies for usage of ALMA and of ALMA data by the user community are presented.
The ALMA Cycle 6 Technical Handbook describes the technical details of ALMA during Cycle 6, including but
not limited to receiver characteristics, array configurations, available observing modes and correlator
setups, and the basis of the OT time estimates.
The ALMA Memo Series and ALMA Technical Notes Series include technical reports on various aspects of
ALMA project development and construction and from the extension and optimisation of capabilities.

4.7

The ALMA Helpdesk

The ALMA Helpdesk is accessed from the ALMA Science Portal or directly at http://help.almascience.org.
Submitted tickets are directed to the registered user’s ARC, where support staff are available to answer any
question related to ALMA, including but not limited to ALMA policies, capabilities, documentation, proposal
preparation, the OT, Splatalogue, and CASA. Users may also request information on workshops, tutorials, orabout visiting an ARC or ARC node for assistance with data reduction and analysis. Users are notified about
the start of Phase 2 of their approved projects via the Helpdesk and can use the project ticket to enquire
about aspects of their project throughout its lifetime. Finally, they can also trigger their ToO observations via
a dedicated department of the Helpdesk (see Section 3.2 ).
Users must be registered at the ALMA Science Portal to submit a Helpdesk ticket. Replies to an alreadyexisting ticket can be sent by the user by logging into the SP or via email (see "Can I respond to my helpdesk
ticket through my email?" for more details). ALMA staff aim to answer Helpdesk tickets within two working
days.
The “Knowledgebase” of the Helpdesk is a database of answered questions or articles on all aspects of
ALMA. Users can search the Knowledgebase to find answers to common queries without submitting a
Helpdesk ticket. Knowledgebase articles that match their query are automatically suggested to users as they
type. The Knowledgebase query interface also searches all the documentation available off the ALMA
Science Portal and provides a direct link to the documentation that may answer a user’s question.

5 Proposal preparation and submission
5.1

Proposal format

An ALMA proposal consists of basic proposal information that is entered directly into the ALMA OT (Section
4.6.1), a Science Justification uploaded to the OT as a PDF file, and one or more Science Goals.
Science Goals contain the technical details of the proposed observations and must include a Technical
Justification. The OT is designed to facilitate proposal preparation and includes a number of tools and checks
to ensure submitted proposals conform to the Cycle 6 capabilities.
After entering the basic proposal information and completing the Science Goals in the OT, the PI cangenerate the PDF of the complete proposal, including Science Justification, Science Goals and Technical
Justification that will be distributed to the ALMA Proposal Review Committee for evaluation.

24

The following sections contain guidelines for preparing the Science and Technical Justification. The setup of
Science Goals is only briefly explained and users are referred to the extensive suite of OT documentation for
details (Section 4.6.1). ALMA novices are encouraged to start with the OT Quickstart Guide and the video
tutorials.

5.2

Preparing the Scientific Justification

ALMA Cycle 6 proposals must include a single PDF document that includes a science case written in English.
The document may optionally include figures, tables and references. The maximum permitted file size is 20
MB.

5.2.1 Page limits
The total length of the PDF document is limited to four pages for Regular, ToO, Solar and mm-VLBI
Proposals and to six pages for Large Programmes (A4 or US Letter format), with a font size no smaller than
12 points. The recommended breakdown is two pages for the science case and two pages for figures, tables,and references, but proposers are free to adjust these numbers within the overall page limit. Large
Programmes are allotted two additional pages, which can be used to further present the scientificjustification and describe the scheduling feasibility, data products, and management plan. It is strongly
suggested that Large Programmes devote at least one page to describe the data products and management
plan.
Figures and tables may be embedded within the science case so that they appear close to the location
where they are referenced in the text. Although the Technical Justification for each Science Goal is enteredin the OT, any figure required for it needs to be placed in the Science Justification PDF document. Users areencouraged to use the LaTeX template developed by ALMA for preparation of their proposals (available atthe Science Portal).
Proposals must be self-contained. Reference can be made to published papers (including arXiv.org preprints)
as per standard practice in the scientific literature. Consultation of those references should not, however, be
required for understanding the proposal.

5.2.2 Science case
Each proposal must describe the astronomical importance of the proposed project and include a clear
statement of its immediate observing goals. It is also recommended to provide a brief justification of therequested sensitivity and angular resolution, with full details provided in the Technical Justification (Section
5.3).
Proposers can simulate ALMA observations using different array components and configurations (seeSection 4.6.2). Simulations are not required. However, if they are discussed in a proposal to justify any
technical aspects of an observation, their results (i.e., images and simulation details) should be included in
the science case and referenced in the relevant Technical Justification.
Since proposal reviewers are selected with expertise that covers the various topics within a proposal
category, the scientific justification should be written for a knowledgeable, but broad-based, audience.

25

5.2.3 Figures, tables, and references
Figures, tables, and references that support the science case and the Technical Justification may be included.
Figure captions, tables and references must use 12-point font and, together with the science case, theymust fit within the overall page length and 20 MB size limit of the PDF proposal.

5.3

Preparing the Technical Justification

Each SG within a proposal must contain a Technical Justification (TJ), which is entered directly into the OT in
the TJ node of each SG. Any figures associated with the TJ must be included in the Science Justification PDF
file and clearly referenced in the TJ. Except for the figures, the TJ must be self-contained, and there should
be no expectation or requirement that the technical assessor reads the Scientific Justification for details. The
TJ must include a quantitative description and justification of the expected source brightness, the requested
sensitivity and S/N ratio, angular resolution and spectral setup. An incomplete Technical Justification may
lead to the rejection of the proposal on technical grounds.
Each SG has its own Technical Justification since the technical setup of the observations will often vary
substantially from one SG to the next. If a Technical Justification is applicable to more than one SG, the TJ
node can be easily copied and pasted between SGs. The TJ node contains three main sections – sensitivity,
imaging, and correlator configuration - corresponding to the main aspects that need to be addressed toassess the technical feasibility of any proposal. Each section includes at least one free-format text box thatmust be filled (50 characters minimum), as well as a number of parameters computed from the user input
captured in that Science Goal. This information is designed to help with the writing of the Technical
Justification, and will also highlight potentially problematic setups (blue text) if applicable. Please see therelevant sections in the OT Reference Manual (accessible by clicking the “?” symbols within the OT) for
details. If the OT detects any technical choices that require an extra justification (e.g. time-constraints),
appropriately labelled text boxes will appear in an additional "Choices to be justified" section.
Given that the information and the text boxes displayed in the TJ node are dependent on information
provided elsewhere in the SG (including the Expected Source Properties entered in the Field Setup node),
the rest of the Science Goal should be set up before filling in the Technical Justification. Specific guidelines
on filling out the Technical Justification are given in Appendix B. Please also see the ALMA OT video tutorial
4: “The technical justification”.
If a proposal does not conform to the advertised capabilities, it can be declared technically unfeasible either
during the proposal review process or during Phase 2 (Section 6.1). The final decision will be made by the
ALMA Director based on the advice from a standing committee consisting of senior staff at the JAO.

5.4

Proposal validation, submission and withdrawal

Once the proposal is validated within the OT, it can be submitted to the ALMA Archive. Validation of Large
Programmes could take up to 5 minutes (or longer!) if the programme contains very complicated setups or alarge number (hundreds) of sources. PIs of such programmes should submit their proposals well before thedeadline. A Cycle 6 proposal can be resubmitted as many times as needed by the PI before the proposal
deadline. With each resubmission, the previous version of the proposal is overwritten (Section 5.4.1).
Submitted proposals cannot be modified after the deadline. For DDT Proposals the first submission is final.

26

Submission of Regular, ToO, Large and mm-VLBI Proposals will be available starting 15:00 UT on 20 March2018 and until the proposal deadline of 15:00 UT on 19 April 2018. No proposal submission or resubmission
will be accepted after the deadline.
In addition, the following considerations apply:•PIs, co-Is and co-PIs can retrieve proposals from the Archive both before and after the deadline.

•

PIs who successfully submit their proposal will receive a confirmation e-mail from ALMA that
includes the assigned project code.

•

Cycle 6 DDT Proposals may be submitted anytime throughout the cycle. Like all other proposals,
they must include a detailed science case and Technical Justification.

•

A Helpdesk ticket should be submitted if the PI needs to withdraw a proposal that has already been
assigned a project code.

5.4.1 Proposal updates
If a PI needs to update and then resubmit a previously submitted Cycle 6 proposal, he/she should ensurethat this is done using the last submitted version. This can be done by either (i) modifying the proposal
saved after submitting it, or (ii) downloading and then modifying the submitted proposal from the Archive. If
an earlier submitted version saved on disk is submitted, it will be rejected by the Archive. An earlier version
that was never submitted (and which therefore contains no proposal code) will produce a new (duplicate)submission with a new code.
Users wishing to generate a new proposal starting from a proposal from the current submission period
should save the original one to disk before it has been submitted. Otherwise, the second proposal willcontain the original proposal’s code and will overwrite it when submitted. Alternatively, the OT's "Open
Project as New Proposal" (available from the File menu) could be used.

5.5

Proposal evaluation and selection

5.5.1 Peer review
ALMA programmes are selected through competitive peer review. The reviewers consist of scientists
selected from the international astronomical community, and are assigned to individual ALMA Review
Panels (ARPs) that are specialized in a scientific category. The ALMA Proposal Review Committee (APRC)
consists of the chairs of each ARP and a Chair, who is selected from the international community by the
ALMA Director.
The JAO assigns each submitted proposal to a panel based primarily on the science category selected by the
PI (see Appendix D for the list of scientific categories), but with care taken to avoid conflicts of interest with
the ARP members.
The APRC will review the Large Programmes selected by the ARPs and will recommend which ones toschedule.
After the outcome of the proposal review process is approved by the ALMA Director’s Council and a Chilean
representative, the results will be communicated to the PIs of submitted proposals. The notifications will27

include the assigned grade and a consensus report from the ALMA review panels that summarises thestrengths and weaknesses of the proposal.

5.5.2 Evaluation criteria
The primary criteria to rank all proposals are the overall scientific merit of the proposed investigation andtheir potential contribution to the advancement of scientific knowledge. The proposals will also be
evaluated to ensure that they are technically feasible and consistent with the Observatory best practices,
unless justified in the proposal.
Given the significant investment of ALMA resources for Large Programmes, the APRC rank will also consider
the following factors for these programmes:•••

Scheduling feasibility
A Large Programme should be designed such that the observations are likely to becompleted within Cycle 6 given the antenna configuration schedule and weather constraints(see Sections 3.3 and 4.3).
Data products
A Large Programme should describe the data products that will be produced to achieve theirscience goals. The programme teams will be expected to deliver these data products to the
ARCs so that they can be made available to the community at large.
Management plan
A Large Programme should present a management plan that describes a schedule of work, adescription of the roles of the proposal team, and a plan to disseminate the results.

5.5.3 Proposal selection
The JAO will take the recommendations of the APRC and form an observing queue based primarily on thescientific ranking from the APRC 5, but taking also into account the scheduling constraints dictated by theconfiguration schedule and weather, the share of observing time for each region and the time available fornon-standard modes.
Up to 33% of the nominal time specified in Section 4.1 will be assigned to Grade A proposals and 67% toGrade B proposals. The total time assigned to Grade A and B proposals will correspond to the nominal
number of hours indicated in Section 4.1, Grade C will be assigned to proposals up to an additional 50% of
the nominal available time, to ensure that an adequate number of projects are available for all
configurations and LST in case the actual observing efficiency or weather conditions differ fromexpectations.
The shares of the observing time among the regions are:••33.75% for the European Organisation for Astronomical Research in the Southern Hemisphere (ESO).
33.75% for the National Science Foundation of the United States (NSF).

Both ALMA and the GMVA VLBI network review and rank the 3mm VLBI Proposals independently, and both must
accept a given proposal for the observations to be scheduled. The ALMA VLBI Coordinating Committee (AVCC) oversees
the merging of the ALMA and VLBI network reviews.

5

28

•
•

22.5% for the National Institutes of Natural Sciences of Japan (NINS).
10% for the Chilean community, which is administrated jointly by the Comisión Nacional deInvestigación Científica y Tecnológica (CONICYT) and the Universidad de Chile.

All regions contribute toward “Open Skies” to enable all eligible Principal Investigators to apply for ALMA
time.

5.6

Proposal confidentiality

For proposals assigned Grade A or B, the project code, the proposal title and abstract, the name and regionof the PI, as well as the names of co-Is (and Co-PIs, in the case of Large Programmes or VLBI Proposals) will
be made public soon after PIs are informed of the outcome of the proposal review process. For proposals
assigned Grade C, the corresponding information will be made public as soon as its first data are archived.
Proposal metadata (for example the source positions, observation frequencies, and integration times) for
Grade A will become public soon after the proposal review process is completed. For Grade B and C
proposals metadata will be made public as soon as the first data are archived. The metadata for unaccepted
proposals or unobserved Grade B or C proposals will remain confidential.
The scientific and technical justifications of all submitted proposals remain confidential, except for proposals
for 1 mm VLBI proposals, which will be sent for review by the EHTC VLBI network.

6 Post-proposal activities
6.1

Observations preparation and submission: Phase 2

Once a project has been approved for scheduling, the project passes into Phase 2. PIs of approved projects
are responsible for checking and approving the Phase 2 material (see ALMA Users’ Policies for further
details). Any changes resulting from the proposal review process or necessitated by technical considerations
will be implemented by the ALMA staff and reviewed by the PI for approval before the SBs are submitted tothe scheduling queue. The PI may request the help of an ALMA Contact Scientist (CS) at the associated ARCor ARC node by replying to the Helpdesk ticket that will be opened on his/her behalf.
Necessary minor changes to the project may also be implemented at this stage as long as they do not impact
the science scope or increase the total execution time. Any change that is more significant must be
requested through the Helpdesk (see Section 6.2).
Once a PI has prepared and approved the Phase 2 material, ALMA staff will make sure the Phase 2 SBs will
run at the telescope and, in case of problems will contact the CS and the PI. If no problems are found, theproject is approved and submitted to the ALMA observing queue to await execution at the telescope. PIs
may track the status of their SBs through the Snooping Project Interface (SnooPI), accessible from the ALMA
Science Portal.
For successful Solar observations, the ALMA Observatory will coordinate with the PI to get an updated target
ephemeris at least 24 hours in advance of the proposed observation.

29

6.2

Changes to submitted programmes

Changes to a submitted proposal will not be permitted prior to the completion of the review process.
Therefore, PIs should carefully check source coordinates, frequency and angular resolution settings andcalibration needs before submitting their proposal and use Helpdesk if they need support.
PIs of proposals assigned a grade of A, B, or C may request changes to their projects subject to the ALMA
Change Request policies described in the Users’ Policies. Minor changes can usually be made during thePhase 2 process by the PI (see Phase 2 QuickStart Guide).
Major changes are allowed only if additional information that may seriously affect the scientific case of the
project has become available since the time of submission, when there is a demonstrable mistake, or when
there is the potential for interesting scientific optimisation.
Change requests are made through the ALMA Helpdesk. The request must include a clear description of the
proposed change along with a clear, substantive justification for the change. Major change requests aretreated case-by-case and evaluated taking into account the increase in science scope, change of observing
time, change from a standard to a non-standard mode, and other factors. Change requests leading to
duplications against ALMA proposals in the observing queue or archival observations will not be approved.

6.3

Data processing and data delivery

ALMA staff will conduct quality assurance on ALMA data and will provide processed data products throughthe respective ARC archives. Quality Assurance Level 2 (QA2) is performed on the data that result from all
executions of an SB. In particular, it is checked that data are calibrated to the desired accuracy and containno significant calibration or imaging artefacts (see ALMA QA2 Data Products for more details). Data thatmeet the PI-specified goals within cycle-specific tolerances (see Chapter 11 of the Technical Handbook) aremade available to the PI. Once the products have been identified as suitable for delivery, the PI is notified
that the data are available for download through the ALMA Archive. PIs are requested to check the delivered
data as soon as practical. For a more complete description of the Quality Assurance process, see Section 6.3of the ALMA Users’ Policies and Chapter 11 of the Technical Handbook.
If the delivered data have problems other than those caused by a mistake of the PI, PIs must submit a QA3
request to the Helpdesk as soon as possible, since this will have implications for the re-observation ofproblematic data and its proprietary period. By default, data obtained as part of an ALMA science
programme are subject to a proprietary period of 12 months (except DDT programmes, which have a 6month proprietary period), starting for each data package when the ARC sends the notification to the PI thatthe data are available (see Sections 8.4.3 and 8.4.4 of the ALMA Users’ Policies).

6.4

Opportunities for public promotion of ALMA

If the PI believes their results are newsworthy or of interest to a broader community, the PI should contact
the ALMA Education and Public Outreach (EPO) team to develop materials for presentation to the media
and the public (e.g. press releases), including support in the preparation of visuals if relevant. EPO may ask
for cooperation on the scientific content and for the PI to be available for possible interviews. The e-mailaddress for the ALMA EPO team is alma-iepot@alma.cl.

30

Appendix A

ALMA Cycle 6 Capabilities

This appendix describes the characteristics and capabilities of the ALMA Observatory that are offered for the
Cycle 6 observing season. All submitted proposals must be compliant with these capabilities or they will be
judged as unfeasible. Where possible, the ALMA Observing Tool has validation checks to warn or prevent
entering un-allowed values.

A.1

Number of antennas

At least forty-three 12 m antennas in the main array (hereafter the 12-m Array) will be offered. The ACA will
have available at least ten 7 m antennas (hereafter the 7-m Array) for short baselines and three 12 m
antennas (hereafter the Total Power Array or TP Array) for making single-dish maps. The ACA will be offeredboth to complement observations with the 12-m Array as well as a stand-alone capability. The stand-alone
ACA is offered either for standard-mode observations only with the 7-m Array or with the 7-m Array and TP
Array combined, but not with the TP Array alone. The use of the TP Array is limited to spectral-line
observations (not continuum) in Bands 3, 4, 5, 6, 7 and 8. Bands 9 and 10 are not available for any TP
observations.
The number of antennas available may sometimes be less than the numbers given above due to unforeseen
problems with the equipment, or during array reconfigurations. ALMA support staff will endeavour toschedule observations that will not be seriously affected by having a slightly smaller number of antennas.
The integration times or uv-coverage might also be increased to compensate whenever this is practical.

A.2

Array configurations

As detailed in Section 4.5, a Science Goal is defined in terms of a desired range of angular resolutions (ARs)and the Largest Angular Structure (LAS) to be imaged. ALMA will meet these requirements by taking
observations in one or more array configurations, which are characterised in terms of their AR and
Maximum Recoverable Scale (MRS, the largest smooth angular structure to which a given array is sensitive –see Chapter 7 of the Technical Handbook for details). The properties of these configurations, and theallowed combinations, therefore define the imaging capabilities of ALMA.
The antennas in the 12-m Array will be staged into configurations that transition from the most compact(with maximum baselines of ~160 m) up to the most extended configuration (maximum baselinesof ~16 km). Ten 12-m Array configurations have been defined to represent the possible distribution of 43
antennas over this range of maximum baselines. These are denoted as C43-x, with x=1 for the most compact
configuration and x=10 for the most extended. One 7-m Array configuration has been defined to represent
the possible distribution of the ten 7 m dishes. The imaging capabilities of these configurations are given in
Table A-1.

31

Table A-1: Angular Resolutions (AR) and Maximum Recoverable Scales (MRS) for the Cycle 6 Array configurations
Config

Lmax

Band 3

Band 4

Band 5

Band 6

Band 7

Band 8Band 9Band 10Lmin

100 GHz150 GHz183 GHz230 GHz

345 GHz460 GHz

650 GHz

870 GHz

7-m
Array

45 m

AR

12.5"

8.4"

6.8"

5.4"

3.6"

2.7"

1.9"

1.4"

9m

MRS

66.7"

44.5"

36.1"

29.0"

19.3"

14.5"

10.3"

7.7"

C43-1

161 m

AR

3.4"

2.3"

1.8"

1.5"

1.0"

0.74"

0.52"

0.39"

15 m

MRS

28.5"

19.0"

15.4"

12.4"

8.3"

6.2"

4.4"

3.3"

314 m

AR

2.3"

1.5"

1.2"

1.0"

0.67"

0.50"

0.35"

0.26"

15 m

MRS

22.6"

15.0"

12.2"

9.8"

6.5"

4.9"

3.5"

2.6"

500 m

AR

1.4"

0.94"

0.77"

0.62"

0.41"

0.31"

0.22"

0.16"

15 m

MRS

16.2"

10.8"

8.7"

7.0"

4.7"

3.5"

2.5"

1.9"

784 m

AR

0.92"

0.61"

0.50"

0.40"

0.27"

0.20"

0.14"

0.11"

15 m

MRS

11.2"

7.5"

6.1"

4.9"

3.3"

2.4"

1.7"

1.3"

1.4 km

AR

0.54"

0.36"

0.30"

0.24"

0.16"

0.12"

0.084"

0.063"

15 m

MRS

6.7"

4.5"

3.6"

2.9"

1.9"

1.5"

1.0"

0.77"

2.5 km

AR

0.31"

0.20"

0.16"

0.13"

0.089"

0.067"

0.047"

0.035"

15 m

MRS

4.1"

2.7"

2.2"

1.8"

1.2"

0.89"

0.63"

0.47"

3.6 km

AR

0.21"

0.14"

0.11"

0.092"

0.061"

0.046"

0.033"

0.024"

64 m

MRS

2.6"

1.7"

1.4"

1.1"

0.75"

0.56"

0.40"

0.30"

8.5 km

AR

0.096"

0.064"

0.052"

0.042"

0.028"

N/A

N/A

N/A

110 m

MRS

1.4"

0.95"

0.77"

0.62"

0.41"

13.9 kmAR0.057"

0.038"

0.031"

0.025"

N/A

N/A

N/A

N/A

368 m

MRS

0.81"

0.54"

0.44"

0.35"

16.2 kmAR0.042"

0.028"

0.023"

0.018"

N/A

N/A

N/A

N/A

244 m

MRS

0.50"

0.33"

0.27"

0.22"

C43-2

C43-3

C43-4

C43-5

C43-6

C43-7

C43-8

C43-9

C43-10Notes for Table A-1:
1. See Chapter 7 of the Technical Handbook for relevant equations and detailed considerations.
2. Values evaluated for source at zenith. For sources transiting at lower elevations, the North-South angularmeasures will increase proportional to 1/sin(ELEVATION).
3. Lmax and Lmin are the maximum and minimum baseline lengths in the array.
4. All angular measures scale inversely with observed sky frequency.
5. Bold blue text indicates non-standard modes (see Table 2).

A.3

Total Power Array

The TP Array is used to recover extended emission when mapping angular scales up to the size of therequested map areas. TP Array observations are included only if the LAS cannot be achieved with the 7-m
Array, and the TP Array can only be used for spectral-line observations (not continuum) in Bands 3–8. No
Band 9 or Band 10 TP Array observations are offered for this cycle. This means that angular scales greater
32

than the 7-m Array MRS listed in Table A-1 cannot be recovered for any observations in Bands 9 and 10, orfor continuum observations in any band.

A.4

Allowed array combinations and time multipliers

Except for simultaneous observations of the 12-m Array with the ACA (Section 1.1), only certain arraycombinations are allowed to meet the specifications of a given Science Goal (SG). A SG can use no more than
two 12-m Array configurations, and 7-m Array observations are only allowed in conjunction with 12-m Arrayobservations if one of the three most compact 12-m Array configurations is required. TP Array observations
are allowed only if 7-m Array observations are also obtained (and subject to the restrictions in the preceding
section). The allowed combinations are indicated in Table A-2 (with empty cells indicating combinations thatare not allowed), and built into the OT validation.
For the resulting data to be combined based on the sensitivity and weighting between the allowed 12-m, 7m and TP Array configurations, the different arrays must be observed in the correct proportion, dependingon the number of overlapping baselines (see Chapter 7 of the Technical Handbook for details). These areexpressed in terms of multiplicative factors with respect to the time required in the most extended
configuration (which in turn is set by the user requested sensitivity and resolution). The time multipliers
adopted are given in Table A-2, and are reported in the OT.
Table A-2: Allowed Array Combinations and Time Multipliers
Most Extended
configuration

Allowed Compact
configuration
pairings

7-m Array

TP

C43-1

7-m Array & TP

C43-2

7-m Array & TP

C43-3

7-m Array & TP

C43-4

C43-7

C43-1 & 7-m Array& TP
C43-2 & 7-m Array& TP
C43-3 & 7-m Array
& TP
C43-4

C43-8

C43-5

C43-9

C43-6

C43-10

-

C43-5
C43-6

Extended
12-m Array
MultiplierMultiplier if
compact 12m Array

Multiplier if
7-m ArrayneededMultiplier if
TP Arrayneeded and

1

1.7

1

7.0

11.9

1

2.4

4.1

1

4.7

1

0.34

1

0.25

1
1
1
1
1

0.26
0.23

2.4
1.2
0.6

8.0
4.0
2.1
1.0

0.22
0.21

Notes for Table A-2:
1. See Chapter 7 of the Technical Handbook for relevant equations and detailed considerations.
2. Whether a more compact array configuration is needed is based on the user specified LAS compared to the
MRS values corresponding to the more extended configuration, as listed in Table A-1. If the LAS is greater thanthe MRS of the extended configuration, a more compact configuration is needed. Conversely, if a morecompact array configuration is not allowed (e.g. for 12-m Array configurations more extended than C43-6), the
LAS is not obtainable and will result in a validation error in the OT.

33

If more than one configuration is needed to satisfy the AR and LAS constraints of a given SG, during Phase 2(Section 6.1), separate Scheduling Blocks (SBs) will be prepared for each required configuration. These will
be observed independently, and the data from the different SBs will be calibrated and imaged separately.

A.5

Receivers

Bands 3, 4, 5, 6, 7, 8, 9 and 10 are available on all antennas. However, observations with Bands 8, 9 and 10
will only be offered for configurations with baselines up to ~ 3.6 km, Band 7 up to ~ 8.5 km, and Bands 3, 4, 5
and 6 up to ~ 16 km (see Section A.2).
There are two types of receivers: dual-sideband (2SB), where the upper and lower sidebands are separated
in the receiver and then processed separately, and double-sideband (DSB), where the sidebands are superimposed coming out of the receiver but may be separated in later processing. All bands receive dual linear
polarizations (X and Y).
Table A-3 summarises the properties of the receiver bands offered in Cycle 6. Details can be found in
Chapter 4 of the Technical Handbook.
Table A-3: Properties of ALMA Cycle 6 Receiver Bands
Band

Frequency range1(GHz)

Wavelength range(mm)

IF range
(GHz)

Type

3

84 – 116

3.6 – 2.6

4–8

2SB

4

125 – 163

2.4 – 1.8

4–8

2SB

5

158 – 211

1.9 – 1.4

4–8

2SB

6

211 – 275

1.4 – 1.1

4.5 – 102SB

7275 – 373

1.1 – 0.8

4–8

2SB

8

385 – 500

0.78 – 0.60

4–8

2SB

9

602 – 720

0.50 – 0.42

4 – 12DSB

10

787 – 950

0.38 – 0.32

4 – 12

DSB

Notes for Table A-3:
1. These are the nominal frequency ranges for continuum observations. Observations of spectral lines that arewithin about 0.2 GHz of a band edge are not possible (at present) in Frequency Division Mode (FDM, see
Section A.6.1), because of the responses of the spectral edge filters implemented in the correlator. IF is theintermediate frequency.

The capability to rapidly switch between receiver bands within the same SG (except for the purposes of datacalibration) is not offered.
Water Vapour Radiometer (WVR) measurements to correct for fluctuations in atmospheric water vapour areavailable for all 12 m antennas. No WVRs are installed in the ACA 7 m antennas and no WVR corrections will
be applied to 7-m Array observations.

34Band 9 and 10 considerations
For Bands 9 and 10 observations, additional uncertainties will affect the data. Since the sidebands can beseparated reliably only in interferometric observations, single-dish Bands 9 and 10 observations with the TP
Array will not be offered in Cycle 6. At Bands 9 and 10, a special correlator mode (90-degree Walsh
Switching) is available. For every spectral window defined by the user, enabling this feature will produce
another spectral window in the other sideband, mirrored around the value of Local Oscillator 1 (LO1). This
doubles the bandwidth of continuum setups in these bands to 16 GHz, thus producing a √2 improvement insensitivity or reducing the time required to achieve a particular sensitivity by a factor of 2. In addition, thegreater bandwidth coverage will allow more spectral lines to be observed simultaneously, although aligning
the spectral windows such that they cover additional transitions is difficult and thus this mode is currently
restricted to the widest-bandwidth spectral windows.
Owing to the complexity of the atmospheric absorption in Bands 9 and 10, calibration will be compromised(this also applies to Band 8 and the high frequency end of Band 7). Bands 9 and 10 ACA 7-m Arrayobservations are more compromised than the corresponding 12-m Array observations, since the rapid
atmospheric phase correction cannot be applied, and the smaller collecting area will limit the network of
usable calibrators; in particular bright calibrators will be sparse at these high frequencies. All these factors,
together with the limited uv-coverage, will affect imaging at Bands 9 and 10 and will limit the achievable
dynamic range with the ACA 7-m Array. Imaging dynamic ranges up to 50 are typical for these bands (seeSection A.9.1 for more details).
No mosaics are offered for Band 10 observations.

A.6

Spectral capabilities

A.6.1 Spectral windows, bandwidths and resolutions
The ALMA Intermediate Frequency (IF) system provides up to four basebands (per parallel polarization) thatcan be independently placed within the two receiver sidebands. For 2SB receivers (Bands 3–8 – see Table
A-3), the number of basebands that can be placed within a sideband is 0, 1, 2, 3, or 4. The placement of thebasebands is restricted for these receivers in that it is not possible to place three basebands in one sideband
and the fourth baseband in the other (see Chapter 6 of the Technical Handbook for details). This restriction
does not apply for DSB receivers (Bands 9 and 10).
The 12-m Array uses the 64-input Correlator, while the 7-m and TP arrays use the 16-input ACA Correlator.
Both correlators offer the same spectral setups. The 64-input Correlator operates in two main modes: Time
Division Mode (TDM) and Frequency Division Mode (FDM). TDM provides modest spectral resolution andproduces a relatively compact data set. It is used for continuum observations or for spectral-line
observations that do not require high spectral resolution. FDM provides high spectral resolution andproduces much larger data sets. A total of six correlator setups with different bandwidths and spectral
resolutions are available (see Table A-4).

35

Table A-4: Properties of ALMA Cycle 6 Correlator Modes, dual-polarization operation 1,2
Bandwidth(MHz)

Channel spacing(3)(MHz)

Spectral resolution(MHz)

Number ofchannels

Correlator mode(4)

1875

15.6

31.2

120

TDM

1875

0.488

0.976

3840

FDM

938

0.244

0.488

3840

FDM

469

0.122

0.244

3840

FDM

234

0.061

0.122

3840

FDM

117

0.0305

0.061

3840

FDM

58.6

0.01530.03053840

FDM

Notes for Table A-4:
1. These are the values for each spectral window and for each polarization, using the full correlator resources
and no on-line spectral binning.
2. Single-polarization modes are also available, giving twice the number of channels per spw, and half thechannel spacing of the above table.
3. The “Channel Spacing” is the separation between data points in the output spectrum. The spectral resolution –i.e., the FWHM of the spectral response function – is larger than this by a factor that depends on the “windowfunction” that is applied to the data to control the ringing in the spectrum. For the default function – the“Hanning” window – this factor is 2. See Chapter 5 of the Technical Handbook for details.
4. Only for the 64-input Correlator

For each baseband, the correlator resources can be divided across a set of “spectral windows” (spw) thatcan be used simultaneously and positioned independently. Up to four spectral windows per baseband areallowed. The correlator can be set to provide between 120 and 3840 channels within each spw, and thefraction of correlator resources that are assigned to each spw sets the number of channels and the
bandwidth available within it. The sum of the fractional correlator resources spread across all spectral
windows must be less than or equal to one (120 or 3840 channels in total).
The default correlator setup for FDM modes averages every two channels. This has the advantage of halving
the data rate to produce more manageable data cubes, while reducing the spectral resolution by only 15%.
However, an additional consideration when selecting the spectral averaging is that data taken over different
time periods (e.g., different configurations or multiple observations within the same configuration) are notguaranteed to be precisely aligned in frequency. Therefore, the spectra will need to be interpolated onto acommon frequency grid in CASA. If the expected line width is poorly sampled at the resolution of thespectrometer, no channel averaging (i.e. a spectral averaging value of 1) is recommended in order toimprove the accuracy of the interpolation (see Chapter 5 of the Technical Handbook for more information).
The instantaneous maximum data rate is 70 MB/s. The OT will issue a validation error if a given SG exceedsthat data rate. For any spectral setup requiring an average data rate of more than 40 MB/s PIs will becontacted during Phase 2 to discuss the possibility to reduce the data rate.
Different correlator modes can be specified for each baseband, but all spws within a given baseband must
use the same correlator mode. For example, a high-resolution FDM mode can be used for spectral-line
observations in one baseband (with up to 4 independently placed FDM spectral windows), while the other36three basebands can be used for continuum observations using the low-resolution TDM mode. And while
each spw within a baseband must use the same correlator mode, they can each be assigned a different
fraction of the correlator resources and each use a different spectral averaging factor, providing a broad
range of simultaneously observed spectral resolutions and bandwidths. Spectral windows can overlap infrequency, although the total continuum bandwidth for calculating the sensitivity is set by the total nonoverlapped bandwidth.

A.6.2 Science Goals with more than one tuning
Users can include up to five tunings per group of sources within 10 degrees in a single SG, except for SGs
that request long-baseline configurations, for which the grouping of sources into clusters will consider only
sources within 1 degree. This enables spectral scans or observations of targets with different radial velocities
within the same SB.
The current calibration scheme for ALMA is to make each SB self-contained in terms of calibration.
Therefore, multi-tuning SGs result in bandpass, amplitude, and gain calibrators being observed for eachtuning in the SB. For SBs that can be completed in a single execution, this is quite efficient. However, for SBs
that require multiple executions, the available time for science targets in each execution is reduced, and theresulting SBs can be quite inefficient. Separating each tuning into its own SG can lead to more efficient SBs
and lower overall time estimates.

Spectral scan mode
A special case of the multiple tuning SG is the “Spectral scan” mode. This is useful for proposers who wish tocarry out spectral surveys or redshift searches. The OT will automatically set up a set of contiguous spectral
windows to cover a specified frequency range. The following restrictions apply:
•
•
•
•
•

Angular resolution and LAS are computed for the Representative Frequency of each SG.
No more than 5 frequency tunings per target are used, all in the same band.
Only one pointing per target is used (no mosaics or offsets allowed).
Only 12-m Array observations can be requested (the ACA is not offered for this mode).
Full polarization cannot be selected.

Spectral scans are categorized as a non-standard mode, limiting the total time available for suchobservations.

A.7

Polarization

In addition to the dual polarization (XX, YY) and single polarization (XX) modes, observations to measure thefull intrinsic polarization (XX, XY, YX and YY) of sources are also offered for 12-m Array TDM and FDM
observations in Bands 3, 4, 5, 6 and 7. The full polarization products can be used to measure both the linear
and circular polarization.
When a Dual Polarization setup is used, separate spectra are obtained for the cross-correlated parallel
hands (XX and YY). These will give two largely independent estimates of the source spectrum that can be
combined to improve sensitivity.

37

In Single Polarization mode, only a single input polarization (XX) is recorded. For a given resolution, thisprovides √2 worse sensitivity than the Dual Polarization case, but one can use either a factor two more
bandwidth for the same spectral resolution (unless the maximum bandwidth was already being used) or afactor of two better spectral resolution for the same bandwidth.
Full Polarization measurements are non-standard, limiting the total time available for such observations.
Sources must have a user-specified largest angular structure that is less than one-third and one-tenth of the
12-m Array primary beam at the frequency of the planned observations for linear polarization and circularpolarization observations, respectively. The expected minimum detectable degree of linear polarization,
defined as three times the systematic calibration uncertainty, is 0.1%(1%) for compact sources and 0.3%(3%)
for extended sources for TDM(FDM) observations, respectively. The minimum detectable degree of circularpolarization is 1.8% of the peak flux for both TDM and FDM observations. Note that the systematic
calibration uncertainty can degrade by a factor of ~2 depending on the quality of the polarization
calibrator and observation conditions (see Chapter 8 of the Technical Handbook for more details). Fullpolarization is not offered for spectral scans or mosaics. The frequency settings for continuum polarization
measurements can be specified by the user, but the OT supplies default setups as detailed in Table A-5. For
FDM mode polarization observations any frequency setting within Bands 3, 4, 5, 6 and 7 is allowed, and thespectral setup has to be the same for the polarization calibrator and the science target.
It should be noted that Full polarization observations require about three hours of parallactic angle coveragefor proper calibration. SGs with properties that lead to a total observing time estimate that is less than threehours will have the time estimate set to three hours to ensure sufficient parallactic angle coverage.
Table A-5: Default frequencies for Continuum Polarization Observations1
Band

spw1
(GHz)

spw2
(GHz)

LO1
(GHz)

spw3
(GHz)

spw4
(GHz)

3

90.5

92.5

97.5

102.5

104.5

4

127.0

129.0

134.0

139.0

141.0

5

196.0

198.0

203.0

208.0

210.0

6

224.0

226.0

233.0

240.0

242.0

7

336.5

338.5

343.5

348.5

350.5

Notes for Table A-5:
1. Fixed central frequencies for four TDM spectral windows, each of width 1.875 GHz, and the corresponding LO1
setting. Frequencies were chosen to optimise spectral performance, and they are centred in known low noiseand low instrumental polarization tunings of the receivers.

A.8

Source restrictions

Source positions are designated by: 1) fixed RA and DEC; 2) RA and DEC at epoch 2000.0 with a linear propermotion; or 3) An ephemeris that is specified that gives the RA and DEC as a function of time. All positions
should be in ICRS (J2000).
At low elevations, it is possible for foreground array elements to block or “shadow” the signal received bybackground antennas, compromising the sensitivity and imaging characteristics of an observation (see38Section 7.3 of the Technical Handbook for details). Therefore, observations of high declination targets
should be avoided, particularly in compact configurations. For the 12-m Array, this shadowing becomessignificant (> 5%) in the most compact configuration for sources with declination lower than −65° or higher
than +20°. The adopted upper declination limit for ALMA is ~+47° (corresponding to a maximum elevation of
20 degrees at the ALMA site) and the OT gives a warning for objects transiting between 20 and 30 degrees
elevation (corresponding to ~+37-47° declination).

A.8.1 Source Science Goal restrictions
A single SG is constrained to include one set of observational parameters that apply to all sources includedin that goal. This includes a single angular resolution, sensitivity, LAS, and receiver band. There is norestriction on the number of SGs per proposal.
For sources distributed widely in the sky the SG will be split by the OT into different “clusters”, eachgrouping all sources within 10 degrees (1 degree for SGs requiring long-baseline configurations). For eachgrouping within the SG, the total number of pointings must be less than or equal to 150. Pointings with the
ACA, if used in concert with 12-m Array observations, do not count against this 150-pointing limit.
The sources in a SG are further subjected to the following restrictions:•••

All the sources in a SG must be defined by the same field setup – either all as rectangular fields, or all
as individual positions.
Sources must use the same spectral setup (relative placement and properties of spectral windows).
For a given group of sources with positions within 10 degrees (1 degree in SGs requesting longbaseline configurations) in the sky the total number of separate tunings cannot exceed 5.

A.8.2 Rectangular Field
A rectangular field (also referred to as a mosaic) is specified by a field centre, the length, width andorientation of the field, and a single spacing between the pointing centres. Observations are conductedusing the “mosaic” observing mode. This repeatedly cycles through all the pointings in the mosaic so thatthe imaging characteristics across the map are similar.
The OT will set up a uniform mosaic pattern based on a user-specified pointing separation, and will calculate
the time to reach the required sensitivity considering any overlap. Non-Nyquist spatial samplings areallowed but must be justified in the Technical Justification. Individual mosaics will not be combined during
post-processing.
If ACA observations are requested as part of a mosaic, then a corresponding 7-m Array mosaic will also be
observed. If these include TP observations, the mosaic area(s) will be covered by the TP Array using on-thefly mapping.
Multiple sources may be included inside a SG, each of which can have a differently sized rectangular field.
The collection of mosaics is subject to the source SG restrictions given above.

39

A.8.3 Individual Pointings
For each field source one or more pointings can be defined at a position of PI's choice and all must overlap
i.e. they must form a single mosaic without gaps. These are often referred to as "custom mosaics" and are
subject to the source SG restrictions given above.
The interferometric data will be combined in post-processing to produce a single image. If ACA observations
are requested as part of a 12-m Array SG, then the corresponding 7-m Array observations will be obtainedusing a Nyquist-sampled mosaic pattern that covers the 12-m Array pointings. If these include TP
observations, the mosaic area(s) will be covered by the TP Array using on-the-fly mapping.
Pointings that do not overlap within a given SG must be included as different field sources within the SG.

A.9

Calibration

The ALMA Observatory has adopted a set of strategies to achieve good calibration of the data (see Chapter
10 of the Technical Handbook). Requests for changes in these strategies will only be granted in exceptional
circumstances and must be fully justified. These changes will make the proposal non-standard (see Section
4.2). The default option is automatic calibrator selection by the system at observing time, but someflexibility exists in choosing the actual calibrator sources in the OT. If users opt for selecting their own
calibrators, justification will be needed. This may result in decreased observing efficiency and/or calibration
accuracy.

A.9.1 Imaging dynamic range
The standard ALMA data reduction with nominal phase stability should be sufficient to produce images withdynamic ranges (peak continuum flux to map rms) up to ~100 for the ACA and the 12-m Array compact
configurations. For configurations more extended than 2 km and at frequency Bands 8, 9 and 10 the imaging
dynamic range may be closer to 50.
Images of bright sources may be dynamic range limited rather than sensitivity limited. Their image quality
may be improved by using self-calibration. For more information please see the Knowledgebase article“What is meant by imaging dynamic range?”.

A.9.2 Flux accuracy
Absolute amplitude calibration will be based on observations of objects of the known flux density of eight
Solar system objects and a set of 40 quasars whose flux density are monitored every 15 days. It is expectedthat the accuracy of the absolute amplitude calibration relative to these objects will be better than 5% forBands 3, 4 and 5; 10% for Bands 6, 7 and 8; and 20% for Bands 9 and 10. The decrease in accuracy at thehigher frequencies is caused by variable atmospheric opacity, pointing errors and coherence loss due tophase fluctuations.

A.9.3 Bandpass accuracy
The amplitude and phase shape of the spectral response for each antenna in the array is measured byobserving a bright source, usually a quasar, for the time needed to reach the desired spectral sensitivity forthe relevant spectral resolution. The accuracy of this shape particularly affects projects that intend to40

observe spectral features that cover a significant fraction of a spw, and/or study faint spectral features in
the presence of strong continuum. Spectral dynamic range (i.e. the desired signal-to-noise ratio per spectral
resolution element) of 1000 has been demonstrated for Bands 3, 4, and 6, and a spectral dynamic range of400, 250, 170, and 150 has been demonstrated for Bands 7, 8, 9, and 10, respectively. Proposals thatrequest higher accuracies may be rejected on technical grounds. For Band 5, a spectral dynamic range limitof 500 may be assumed, but users should note that this has not yet been verified.

A.9.4 Total Power calibration
The intensity calibration for single-dish observations with the TP Array is made by using the Amplitude
Calibration Device (ACD), which results in an intensity scale in terms of the corrected Rayleigh-Jeans antenna
temperature TA* (K). To combine the TP data with the interferometric data the intensity scale is converted
from K to Jy. The conversion factor is a function of the observed frequency, half-power beam width, andaperture efficiency of the TP Array antennas. The latter two are derived from regular single-dish calibration
observations. The overall accuracy for the total power calibration is about 5% at Bands 3, 4, 5, 6 and 7,
increasing to 15% at Band 8.

A.9.5 Astrometry
The absolute positional registration of an ALMA image on the sky depends on the angular resolution and thequality of the phase calibration. For the standard calibration with average phase conditions, the typicalimage registration accuracy is ~ (angular resolution)/20.0 but with a minimum of 0.003", without special
calibrations. This assumes that the S/N ratio of the target image is at least 20:1 to reach this accuracy. For
projects for which measuring the position of an object or its motion over a period of time is a main goal,
recommendations for Cycle 6 are:
•
•

•
•

Choose a calibrator with a VLBI position as close to the target as possible, using spw and polarization
averaging for weaker calibrators.
Confirm the observations contain a secondary calibrator of known position (and justify it in theTechnical Justification), so its measured position after normal calibration is an indication of theastrometric accuracy of the observations.
Choose the observing frequency and configuration to maximise the astrometric precision of thetarget, based on its angular size and spectral properties.
If the desired astrometric precision is better than about 0.003" rms, then multiple calibrators should
be observed. Further details and guidelines are given in Chapter 10 of the Technical Handbook.
Proposers are also encouraged to discuss the experiment with their local ARC.

A.10 Time-constrained observations
Observations of monitoring and time-constrained projects are offered subject to the following restrictions:•Observations to be performed with two 12-m Array configurations to satisfy the PI requests of AR
and LAS within a SG are not allowed to have time constraints.

•

Observations with one 12-m Array configuration and the ACA are allowed to have time constraints
only if simultaneous observations with the two arrays have been requested.

41

•No restrictions will be imposed on the size of the time window specified by PIs for time-criticalobservations. The scheduling feasibility of any proposal will depend on the total number of
constraints that are imposed and on whether the time window takes place during other activities on
the array such as engineering or computing time. Whether such observations are technically feasible
will be decided on a case-by-case basis. In particular, observations with strict timing constraints but
many possible time windows may be feasible.

•

Programmes that require more than two hours of continuous observations to monitor a sourcecannot be guaranteed due to variable weather conditions and system interruptions. Proposers may
request monitoring observations longer than two hours, but if the observations fail after two hours,
the observations will not be repeated. Monitoring observations will be interrupted by regularcalibrations.

Stand-alone ACA proposals requesting only observations on the 7-m Array are allowed to have time
constraints.

A.11 Solar observations
Proposals will be accepted for ALMA interferometric and total power observations of the Sun with thefollowing capabilities and restrictions:•

Solar observations will be conducted only during the periods when the 12-m Array is in one of thethree most compact configurations (maximum baselines less than 500 m; see configuration schedulein Section 4.3.3). There will be no dedicated “solar campaign” during those configurations, but theobservations may be executed at any time.

•

The interferometric component of Solar observations will be conducted using a special combinedarray comprising both 12 m and 7 m antennas (to ensure sufficient short-spacing information isobserved), and will be processed with the 64-input Correlator (Section 5.1 of the TechnicalHandbook). Observations with only the 12-m Array or only the 7-m Array are not offered.

•

To minimise shadowing of 7 m antennas, observations will be carried out between 10:00 and 17:00
CLT (13:00 UT and 20:00 UT).

•

PIs may designate a desired range of angular resolutions. This is restricted to the range provided by
one of the three most compact 12 m configurations (see Section A.2).

•

The Total Power component of Solar observations consists of fast-scanning mapping observations of
the full Sun to recover the largest angular scales for interferometric observations. Proposals
requesting only total-power single-dish observations will not be accepted. The Total Powerobservations will be taken contemporaneously with the interferometric observation. Theseobservations will not be executed when the Sun is at elevations above 70⁰ because the required
fast-scan azimuth slew speeds are too high. The time cadence of full-sun images obtained from total
power observations is about 7 minutes for Band 3 and 10 minutes for Band 6.

•

Proposers will specify their Solar target by providing a target position in Heliocentric coordinates.
The ALMA Observatory will coordinate with successful PIs to get an updated target position at least42

48 hours in advance of the proposed observation. The interaction will be done via the Helpdesk. The
ALMA Solar Ephemeris Generator tool is available for PIs to help them generate the ephemeris.
•

Only proposals for continuum observations in Bands 3 and 6 will be accepted. For interferometricobservations, these will be obtained using the low spectral resolution (TDM) mode (see Section
A.6.1). The individual integration times for this mode are fixed to 1 second, and the frequencies are
fixed to four 1875 MHz-wide spectral windows centred on the frequencies shown in Table A-6. The
high spectral resolution (FDM) observing mode is not offered for Solar observations.

•

The observing frequencies of the total power observations are as shown in Table A-6, but the total
power data only include one channel per spw; a correlator will not be used for total power
observations in Cycle 6 and so autocorrelation measurements will not be available.
Table A-6: Observing frequencies for Cycle 6 Solar observations
Band

spw1
(GHz)

spw2
(GHz)

LO1
(GHz)

spw3
(GHz)

spw4
(GHz)

3

93.0

95.0

100.0

105.0

107.0

6

230.0

232.0

239.0

246.0

248.0

•

Simultaneous observations with Bands 3 and 6 are not offered: each Science Goal can only include
one band.

•

Observations may be performed using dual linear polarization (XX, YY) or single polarization (XX)correlations; full polarization measurements are not currently offered for Solar observations.

•Because the WVR receivers are saturated when the antennas point at the Sun, the on-line WVR
phase correction will not be applied and the off-line WVR correction for on-source (Solar) data is notpossible.

•

Absolute calibration of single-dish brightness temperatures is currently no better than ~10% but ismore realistically ~15%. While efforts are on-going to improve Solar calibration, Science Goals that
require absolute temperatures more accurate than this, and in particular comparisons of absolutetemperatures between Bands 3 and 6, will be difficult to carry out successfully.

A.12 VLBI observations
Proposals will be accepted for ALMA VLBI (phased array) observations, with the following capabilities andrestrictions:•

VLBI observations will be conducted using a “campaign mode”, whereby specific dates are reserved
for the execution of VLBI programmes in coordination with the other facilities in the VLBI networkand so that VLBI experts are available to help with programme execution. Observing windows will beidentified during the periods when the 12-m Array is in one of the three most compact
configurations (maximum baselines less than 500 m; see configuration schedule in Section 4.3.3).
The actual campaign dates will be set after the proposal review process.

•Due to the need to phase up on the target source, only targets with correlated flux densities > 0.5 Jy
43

on intra-ALMA baselines out to 1 km may be proposed for observation for both Bands 3 and 6.

•

Only proposals for continuum observations in Bands 3 and 6 will be accepted. These will be obtainedin full polarization using the high spectral resolution (FDM) mode (see Section A.6.1) and the 64input Correlator. Observing frequencies are fixed to four 1875 MHz-wide spectral windows centredon the frequencies shown in Table A-7 below.
Table A-7: Observing Frequencies for Cycle 6 VLBI Observations

•

•

•

Band

spw1
(GHz)

spw2
(GHz)

LO1
(GHz)

spw3
(GHz)

spw4
(GHz)

3

86.26888.26893.26898.268100.268

6

213.1

215.1

222.1

227.1

229.1

The proposers are required to enter a VLBI total time requested. Here, they should enter the amountof time requested for ALMA (and not the total time requested to the GMVA/EHTC networks, which
may be longer). Note that this time must include overheads. For ALMA + GMVA or EHTC the total
observing time (including overheads and ALMA calibrations) is a factor of four (25% duty cycle) of the
expected time on source.
A VLBI session will not exceed one week. Therefore, if multi-epoch observations are requested, theymust fit within one week and the total time must be the aggregate time of all observations.
A minimum of three observing hours is required to make a clean linear to circular transformation of
the data.

For 3 mm VLBI, a proposal must have been submitted to the GMVA network by their 1 February 2018
deadline (see the GMVA website that also provides a sensitivity calculator). Another sensitivity calculator isavailable at the European VLBI Network site.
For 1 mm VLBI, the ALMA Observatory will forward the submitted 1 mm VLBI proposals to the EHTC network
for technical assessment. Thus, proposers do not need to send their proposal to the EHTC.

44

Appendix B

Technical Justification guidelines

The Technical Justification must be entered directly into the OT for each Science Goal. Below are guidelines
on issues to consider in the different sections. Sections B.5 and B.6 point to specific items that needjustification for Solar and VLBI observations, respectively. In general, PIs should address all the parameters
requested in the OT.

B.1

Sensitivity

At the top of the sensitivity section, the OT will display the sensitivity and S/N ratio achieved for different
bandwidths (bandwidth requested for sensitivity, aggregate bandwidth, a third of the line width) as
appropriate for the spectral setup and the Expected Source Properties defined. While the justification for
the requested sensitivity or S/N ratio should be included in the Scientific Justification (Section 5.2.2), the TJ
must explain which sensitivity or S/N ratio are expected for all the parts of the spectrum that are of interest,
e.g. for a spectral setup targeting a weak and a strong spectral line as well as the continuum, and the meansby which the proposed technical setup will achieve those requests.
The fluxes in the Expected Source Properties must be entered per synthesized beam, i.e. proposers may
have to correct any available flux measurements for the fact that the requested source is spatially resolved
by ALMA and the flux is distributed over several synthesised beams (see Knowledgebase articles “How can I
estimate the Peak Flux Density per synthesised beam using flux measurements in Jy or K from otherobservatories?” and “How do I convert flux measurements given in Jy km/s or K km/s into the peak flux
density required by the OT?” and this video for more details on using fluxes/brightness temperatures fromother facilities).
Users should be aware that the sensitivity requested may not be achievable in practice if the observations
are dynamic range limited; e.g. when the field of view contains another, very bright, source or the spectrum
has very bright lines. S/N values smaller than three trigger a blue informative message and need to be fully
justified; they may lead to a rejection of the proposal on technical grounds if no adequate explanation is
given. For setups including spectral lines, another value to double-check is the ratio of the line width(entered in the Expected Source Properties) over the bandwidth used for sensitivity (from the Control &Performance editor), which is conveniently displayed by the OT. It is important to understand that thesensitivity requested will be achieved over a frequency bin corresponding to this bandwidth, not necessarily
over every spectral resolution element. For spectral-line measurements this value should normally be larger
than three (or even higher if you want to measure the shape of the line profile). An informative message willappear if this is not the case, and PIs should address this issue in the justification text (e.g. if the sensitivity
requirement is driven by the continuum it may be acceptable to have a very low ratio).
The final parameter to be checked for observations measuring both line and continuum emission is the
spectral dynamic range, defined as the continuum peak flux divided by the line rms. Limits on the spectral
dynamic ranges offered in Cycle 6 for the different ALMA bands are given in Appendix A (Section A.9.3); an
informative message will appear if these are exceeded and the proposal may be rejected on technicalgrounds. The spectral dynamic range is important especially when trying to detect a weak line on top of astrong continuum, and high spectral dynamic ranges may require a better bandpass accuracy than possible

45

with a standard calibration. If a high spectral dynamic range is required, extra bandpass calibrations mayneed to be obtained selecting “User-defined calibration”.

B.2

Imaging

When planning ALMA observations, in addition to the sensitivity goals, the complexity of the emission in thescience target field should also be considered. An interferometer's ability to reconstruct complex emission is
directly related to the uv-coverage of the data. This section is used to justify the requested AR and LAS,
which for convenience are reported back by the OT. The AR and LAS needed to image complex emission
should be carefully justified (if necessary, including simulations), especially if multiple antennaconfigurations are required. The number of required antenna configurations is listed in the observing time
estimate of the project time summary in the OT.
The ''snapshot'' (i.e. short observation) uv-coverage of the more compact ALMA configurations (C43-1 toC43-3) is excellent (see Section 7.5 of the Technical Handbook), it is still reasonably good for C43-4 to C43-6,
but for the longer baseline configurations (C43-7 to C43-10) the uv-coverage is quite sparse even with 50
antennas. As such, more observing time must be spent to “fill in” as much as possible the missing uvcoverage. Thus, high fidelity imaging of complex and/or high dynamic range emission may require a longer
observing time than implied by sensitivity requirements alone, and this is especially true for the longbaseline configurations. Consecutive executions of a given SB (if needed) are favoured during scheduling inorder to maximise uv-coverage. Nonetheless, if more extensive uv-coverage is required to satisfy theimaging requirements, the OT's sensitivity-based time estimate can be overridden (see below). PIs arestrongly encouraged to use the ALMA simulator tools to assess the potential need for extra uv-coverage.
For single or non-overlapping pointings the source should fit within the inner one-third of the primary beam(field of view), or the PI should discuss the effects of the sensitivity loss towards the beam edges.
PIs should also pay attention to the expected image dynamic range (see Section A.9.1) if attempting todetect a weak signal that falls in the same pointing as a much brighter source. The OT cannot identify suchcases automatically since it has no knowledge of the flux structure of the field to be observed. See theKnowledgebase article “What is meant by imaging dynamic range?” for details.

B.3

Correlator configuration

For spectral-line observations, the OT reports the number of (Hanning smoothed) spectral resolution
elements per line width, taking into account any spectral averaging, and the width of the representative
spectral window. PIs have to make sure to select the correct representative spectral window. If the spectral
resolution is larger than one third of the line width from the Expected Source Properties, an informative
message will appear, and if not suitably justified this will lead to the rejection of the proposal on technicalgrounds. Note that the spectral resolution is not necessarily the same as the bandwidth for sensitivity!
The requested correlator setup and the placement of spectral windows should be carefully justified in thefree-format text box. In the case of multiple spectral lines and/or narrow spectral windows in particular, PIs
should double-check that the line profiles are fully covered by the selected spectral windows.
PIs should also check whether any of the spectral windows are severely impacted by atmosphericabsorption, which can affect Bands 5 and 7-10 especially. If necessary, the representative frequency should46

be modified to be at the most restrictive part of the atmosphere where a line needs to be detected, which
will impact the time estimate. Any continuum windows should be moved to avoid areas of bad transmission.
For the double sideband receivers (Bands 9 and 10), the atmospheric transmission in the mirrored spectral
window due to the 90 degree Walsh Switching (Section A.5) impacts the sensitivity achieved in the spectral
window and therefore the time estimate. PIs may wish to modify the spectral setup accordingly. It isadvisable to add continuum spectral windows in any unused basebands, in particular for high frequency SGs.
For sources with known high line density (~1 spectral feature per 10 MHz), PIs are encouraged to set up all
the spectral windows in FDM mode. This will allow a more robust determination of the line-free channels
used to form the aggregate continuum during data processing and imaging.

B.4

Choices to be justified

The OT will automatically catch a number of user choices that must be explicitly justified in a text box. These
choices are:•Override of OT's sensitivity-based time estimate: Proposers may wish to override the OT's time
estimate to monitor a source over a certain time range or to build up the uv-coverage for imaging acomplex source. When using this option, proposers should keep in mind that programmes that
require more than two hours of continuous observations cannot be guaranteed due to variable
weather conditions and system interruptions (Section A.10). The time entered refers to the 12-m
Array time, includes all calibrations, and must be fully justified. Note that the OT assigns the PWV
based on the representative frequency of the requested observations and the declination of thesource to ensure data quality. Thus is not possible to request specific weather conditions for theobservations.

•Time-constrained observations: the OT allows you to specify two types of time-constrained
observing: single visit and multiple visits. In the first case, one or more time windows are specified,
but the observations will only be carried out once during any of these time windows. In the second
case, the Science Goal is observed in each of the time windows specified. The technical feasibility oftime-constrained observations will be decided on a case-by-case basis.

• User-defined calibration: the default system-defined calibration option ensures that the proper
calibrations for the flux scale, bandpass, and relative antenna gains are obtained. Observations
making use of the full polarization capabilities of ALMA will also include the necessary calibrations
by default. User-defined calibrations should be necessary only in rare cases, e.g. if a very highspectral dynamic range is required, it may be necessary to perform additional calibrations and/or
use specific sources. Such requests must be explained and justified in detail. Programmes thatcannot be calibrated or that increase significantly the complexity of data reduction will not beallowed and flagged as technically unfeasible and rejected.
•

Low maximum elevation: sources that transit at a low elevation are difficult to schedule forobservation since they suffer from high atmospheric attenuation and require low PWV, especially athigh frequencies (see Section A.8). A detailed explanation should be provided as to why thesesources need to be observed rather than sources at higher elevation.

47

•Single polarization: this should only be used when the highest spectral resolution is required, as thesensitivity achieved is lower than when using the default dual polarization. PIs should carefully
justify why the high spectral resolution requested is required.

•

Sparser sampling than the default λ/√3D (Nyquist sampling) can be more effective at covering large
areas more quickly, at the price of less uniform spatial coverage and noise. Deviating from thedefault mosaic sampling must be justified scientifically, and is to be avoided when imaging
extended sources, particularly if image fidelity is an important concern.

B.5

Solar observations

The sensitivity calculator is not adequate for Solar observations because the antenna temperature greatly
exceeds the system temperature and, moreover, depends on the Solar target (e.g., quiet Sun, active region,
Solar limb). Therefore, Solar proposers are asked to enter the total time and justify this request to the extent
that depends on technical imaging considerations, not on scientific factors. For example, for a mosaic of atarget in a given frequency band, PIs should indicate how many repetitions of the sampling pattern areneeded and why. For this calculation PIs should take into account that ALMA observations are comprised of
one or more executions of a SB. The total execution time of an SB cannot exceed 2 hours, which will include
the time overheads for bandpass and flux calibration. These calibration overheads amount to about 25 mins.

B.6

VLBI observations

The VLBI Technical Justification should be tuned to the overall science goals taking into account the phased
ALMA array.
As a guideline, the ALMA Technical Justification should include the reasons for using the 1.3 or 3 mm bands,
the flux density of the target on a 1 km baseline, correlated flux densities on baselines longer than 5000 km,
the total observing time requested (including time for calibration), and potential bandpass, polarization anddelay calibrators. If polarimetry is requested, the expected S/N ratio for the polarized emission should bestated. If imaging is requested, imaging considerations should also be mentioned (e.g. dynamic range issues,complex source structure, etc.) as well as any special technical requirements with either the set up or thedata processing. Finally, the proposers should specify the EHT or GMVA stations that are requested for VLBI.
Due to the need to phase up on the target source, only targets with correlated flux densities > 0.5 Jy on
intra-ALMA baselines out to 1 km may be proposed for observation for both Bands 3 and 6. The following
on-line material is currently available to help justify the requested observing time:•At 3 mm: the sensitivity calculator and the 3 mm VLBI page.

• At 1 mm: the 1 mm VLBI page and links.

48

Appendix C
ACA
ACD
ALMA
AOS
APEX
ARC
ARP
APRC
AR
ASC
ASIAA
AUI
CASA
Co-I
Co-PI
CONICYTCSDDTEA ARC
EHTC
EPO
ESO
EU ARC
FDM
FOV
GMVA
IF
KASI
JAO
LAS
LO1
LSRK
LST
MRS
NA ARC
NAASC
NAOJ
NINS
NRAO
NRC
NSC
NSF
OSF
OST
OT

Acronyms and abbreviations

Atacama Compact Array
Amplitude Calibration Device
Atacama Large Millimeter/submillimeter Array
Array Operations Site
ALMA Pathfinder EXperiment
ALMA Regional Center (for EA and NA) or Centre (for EU)
ALMA Review Panel
ALMA Proposal Review Committee
Angular Resolution
ALMA Sensitivity Calculator
Academia Sinica Institute of Astronomy and Astrophysics
Associated Universities, Inc.
Common Astronomy Software Applications
Co-Investigator
Co-Principal Investigator
Comisión Nacional de Investigación Científica y Tecnológica
Contact Scientist
Director’s Discretionary Time
East Asian ALMA Regional Center
Event Horizon Telescope Consortium
Education and Public Outreach
European Organisation for Astronomical Research in the Southern Hemisphere
European ALMA Regional Centre
Frequency Division Mode
Field Of View
Global Millimetre VLBI Array
Intermediate Frequency
Korea Astronomy and Space Science Institute
Joint ALMA Observatory
Largest Angular Structure
Local Oscillator 1
Kinematic Local Standard of Rest
Local Sidereal Time
Maximum Recoverable Scale
North American ALMA Regional CenterNorth American ALMA Science Center
National Astronomical Observatory of Japan
National Institutes of Natural Sciences
National Radio Astronomy Observatory
National Research Council of Canada
National Science Council of Taiwan
National Science Foundation
Operation Support Facility
Observation Support Tool
Observing Tool

49

OUS
PDF
PI
PWV
QA2
SB
SCO
SG
S/N
SnooPI
SP
Spw
TDM
TJ
ToO
TP
VLBI
WVR

ObsUnitSet
Portable Document Format
Principal Investigator
Precipitable Water Vapour
Quality Assurance Level 2
Scheduling BlockSantiago Central Office
Science Goal
Signal-to-noise
Snooping Project Interface
Science Portal
Spectral window
Time Division Mode
Technical Justification
Target of Opportunity
Total Power
Very Long Baseline Interferometry
Water Vapour Radiometer50

Appendix D

Science categories and keywords

The list below presents the available science categories and the corresponding keywords that can be used in
the OT to further specify the scientific area of the proposal. Proposers must select at least one and at most
two keywords.

Category 1 – Cosmology and the high redshift universe
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.

Lyman Alpha Emitters/Blobs (LAE/LAB)
Lyman Break Galaxies (LBG)
Starburst galaxies
Sub-mm Galaxies (SMG)
High-z Active Galactic Nuclei (AGN)
Gravitational lenses
Damped Lyman Alpha (DLA) systems
Cosmic Microwave Background (CMB)/Sunyaev-Zel'dovich Effect (SZE)
Galaxy structure & evolution
Gamma Ray Bursts (GRB)
Galaxy Clusters

Category 2 – Galaxies and galactic nuclei
a. Starbursts, star formationb. Active Galactic Nuclei (AGN)/Quasars (QSO)
c. Spiral galaxies
d. Merging and interacting galaxies
e. Surveys of galaxies
f. Outflows, jets, feedback
g. Early-type galaxies
h. Galaxy groups and clusters
i. Galaxy chemistryj. Galactic Centres/nuclei
k. Dwarf/metal-poor galaxies
l. Luminous and Ultra-Luminous Infra-Red Galaxies (LIRG & ULIRG)
m. Giant Molecular Clouds (GMC) properties

51

Category 3 – ISM, star formation and astrochemistry
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.

Outflows, jets and ionized winds
High-mass star formation
Intermediate-mass star formation
Low-mass star formation
Pre-stellar cores, Infra-Red Dark Clouds (IRDC)
Astrochemistry
Inter-Stellar Medium (ISM)/Molecular clouds
Photon-Dominated Regions (PDR)/X-Ray Dominated Regions (XDR)
HII regions
Magellanic Clouds

Category 4 – Circumstellar disks, exoplanets and the solar system
a.
b.
c.
d.
e.
f.
g.
h.
i.

Debris disks
Disks around low-mass stars
Disks around high-mass stars
Exoplanets
Solar system: Comets
Solar system: Planetary atmospheres
Solar system: Planetary surfaces
Solar system: Trans-Neptunian Objects (TNOs)
Solar system: Asteroids

Category 5 – Stellar evolution and the Sun
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
m.
n.
o.

The SunMain sequence stars
Asymptotic Giant Branch (AGB) stars
Post-AGB stars
Hypergiants
Evolved stars: Shaping/physical structure
Evolved stars: Chemistry
Cataclysmic stars
Luminous Blue Variables (LBV)White dwarfs
Brown dwarfs
Supernovae (SN) ejecta
Pulsars and neutron stars
Black holes
Transients52