# Presentation: 696031

## The Large Synoptic Survey Telescope

**Presentation to AAAC**
**October 13, 2006**
- Anthony Tyson
- Director, LSST
- Physics Department, Univ. of California, Davis

## Large Synoptic Survey Telescope 

**History**:
- The need for a facility to survey the sky *Wide, Fast and Deep*, has been recognized for many years.
- 1996-2000 “*Dark Matter Telescope”*
- Emphasized* *mapping dark matter
- 2000-    “*LSST”*
- Emphasized a broad range of science from the same multi-wavelength survey data

## Wide+Deep+Fast:  Etendue

**Wide+Deep+Fast:  *****Etendue***

- Primary mirror
- diameter

- Field of view

- Keck
- Telescope

- 0.2 degrees

- 10 m

- 3.5 degrees

- LSST

**  ****4 billion galaxies with redshifts**
**  ****Time domain: **
**     ****100,000 asteroids**
**     ****1 million supernovae**
**     ****1 million gravitational lenses**
**     ****gamma ray bursters**
**     ****new phenomena**

**LSST survey of 20,000 sq deg**

## Relative Etendue (= A)

- All facilities assumed operating100% in one survey

**15 sec exposures**

**2000 exposures per field**

## 

**Opening Time Domain**

## deep  wide fast

***deep  wide fast***

## LSST Survey

** ****6-band Survey:  u*****grizy  ***** 320–1050 nm**
**    ****Frequent revisits:  grizy**
** ****Sky area covered:          >20,000 deg****2****       **
**                                          ****0.2 arcsec / pixel**
** ****Each 10 sq.deg FOV revisited ~2000 times**
** ****Limiting magnitude:    27.7 AB magnitude  @5******
**                                         ****25   AB mag /visit = 2x15 seconds**
** ****Photometry precision:   0.01 mag requirement, **
**                                            ****0.001 mag goal**

##  Massively Parallel Astrophysics

-  **Dark matter/dark energy via weak lensing **
** ****Dark matter/dark energy via baryon acoustic oscillations**
** ****Dark energy via supernovae**
** ****Dark energy via counts of clusters of galaxies**
** ****Galactic Structure encompassing local group**
** ****Dense astrometry over 20000 sq.deg:  rare moving objects**
** ****Gamma Ray Bursts and transients to high redshift**
** ****Gravitational micro-lensing**
** ****Strong galaxy & cluster lensing: physics of dark matter**
** ****Multi-image lensed SN time delays: separate test of cosmology**
** ****Variable stars/galaxies: black hole accretion**
** ****QSO time delays vs z: independent test of dark energy**
** ****Optical bursters to 25 mag: the unknown**
** ****5-band 27 mag photometric survey: unprecedented volume**
** ****Solar System Probes: Earth-crossing asteroids, Comets, trans- Neptunian objects**

## LSST Ranked High Priority

**NRC Astronomy Decadal Survey**
**NRC New Frontiers in the Solar System**
**NRC Quarks-to-Cosmos**
**SAGENAP**
**Quantum Universe**
**Physics of the Universe**
**Dark Energy Task Force  +  P5**

## LSST Funding Timeline 

**LSST Funding Timeline**** **

***   ******FY-2004    *****R&D proposal to NSF AST**
**   ****FY-2005    $14.2M  LSST R&D grant**
**   ****FY-2006    DOE CD-0  Ground-based dark energy**
***   ******FY-2007     LSST NSF MREFC Proposal submitted***
***   ******FY-2009     NSB moves LSST to readiness phase***
***   ******FY-2009     DOE MIE funding begins for camera ***
***   ******FY-2010     NSF MREFC award to begin construction ***
***   ******FY-2014     First light and commissioning***

## LSST Probes Dark Energy and Dark Matter

**Weak lensing (multiple probes)**
**Baryon acoustic oscillations **
**Counts of massive structures vs redshift**
**Supernova cosmology (complementary to JDEM)**
**Mass power spectrum on very large scales tests CDM paradigm**
**Shortest scales of dark matter clumping tests models of dark matter particle physics**

***The LSST survey will address all with a single dataset!***

## Weak Gravitational Lensing Heritage

- 2-degree by 2-degree mass map of one of five Deep Lens Survey  fields. All four clusters examined in this field have been verified with spectroscopy and X-ray observations (2005)

***1983-2000 ***** Weak gravitational lens experiments using Blanco telescope**
***2000  *****First detection of cosmic shear **
***2000-2005  *****Deep Lens Survey**
***1996-  *****Emerging need for an all-sky deep multi-wavelength facility with controllable systematic errors**

***Today, several distinct groups***
***worldwide are pursuing weak ***
***lens cosmology on a variety***
***of telescopes.***

## 20000 sq.deg WL survey shear power spectra

- z=3.0

**20000 sq.deg WL survey shear power spectra**

- z=1100

- z=3.2

- z=0.2

- z=0.6

- LSST shear systematics floor

- 0.001 shear

- Blanco shear systematics floor

- z=3.2

- z=0.2

***Require: shear error < 0.0002***

- 0.01 shear

- 0.001 shear

## Addressing DETF Critical Issues

- WL shear reconstruction errors
- Show control to better than required precision using existing new facilities  
- Photometric redshift errors
- Develop robust photo-z calibration plan 
- Undertake world campaign for spectroscopy 
- Photometry errors
- Develop and test precision flux calibration technique 

## Subaru 10 sec Exposures 

- Raw

- de-trailed

- PSF corrected

**<shear> **
** ****= 0.07**

**  ****<shear> **
**= 0.000013**

**13 arcmin  (*****l *****= 1000)**

**<shear> **
** ****= 0.04**

**Single exposure in 0.65 arcsec seeing**

**<shear> **
** ****< 0.0001**

## Residual Subaru Shear Correlation

**Cosmic shear signal**

**Test of shear systematics: **
**Use faint stars as proxies for galaxies, and calculate the shear-shear correlation.**
**Compare with expected cosmic shear signal.**
**Conclusion: 500 exposures per sky patch will yield negligible PSF induced shear systematics. Wittman (2005)**

## Photometric Redshifts

**Photometric Redshifts**

- Calibration: angular correlation between photo-z and spectroscopic samples enables high precision photo-z:   http://www.lsst.org/Science/Phot-z-plan.pdf

**Precision calibration plan:  underway.  Likely will exceed requirements.**

## 12-band Super Photo-z Training Set

- Using angular correlations this training set enables LSST photo-z error calibration to better than required precision

- Systematic error:
- 0.003(1+z)  _*calibratable*_
- Need 20,000 spectroscopic redshifts

## Baryon Acoustic Oscillations

- R**S**~140 Mpc

**Standard Ruler**
**Two Dimensions on the Sky**
**     ****Angular Diameter Distances **
**Three Dimensions in Space-Time**
**     ****Hubble Parameter**

**Baryon Acoustic Oscillations**

- CMB (z = 1080)

- BAO (z < 3)

## LSST Precision on Dark Energy 

- WL+BAO and Cluster counts give separate estimates.  Both require wide sky area deep survey.

- Zhan 2006

## Dark Energy Precision vs time

**Combined**

**Separate DE Probes**

- More than 10x DETF
- Stage-IV FOM goal

## LSST Project Organization

**LSST Project Organization**

**The LSST is a public/private project with public support through NSF-AST and DOE-OHEP.**
**Private support is devoted primarily to project infrastructure and fabrication of the primary/tertiary and secondary mirrors, which are long-lead items.**
**NSF support is proposed to fund the telescope.  DOE support is proposed to fund the camera.**
**Both agencies would contribute to data management and operations.**

- LSST Organization Chart

## The LSST Corporation

- The project is overseen by the LSSTC, a 501(c)3 non-profit Arizona corporation based in Tucson.
- LSSTC is the recipient of private funding, and is the Principal Investigator organization for the NSF D&D funding.

## LSSTC member institutions 

**16 current member institutions.**
***Google Corp. has applied.***
***More pending.***
**+ Several foreign groups.**

## Foreign prospective members

-   German university group (led by Matthias Steinmetz)
-   French group (IN2P3 Collaboration)
-   UK university group (led by Andrew Lawrence)
-   European Southern Observatory (Catherine Cesarsky, Dir)

## LSST integrates Astronomy & Physics communities

**astronomy**

-   particle
- physics

**LSST**
**Project**

**NSF**

**DOE**

- LSST Collaborations

## LSST Science Collaborations 

**Supernovae: M. Wood-Vasey (CfA) **
**Weak lensing: D. Wittman (UCD) and  B. Jain (Penn)**
**Stellar Populations: Abi Saha (NOAO) **
**Active Galactic Nuclei: Niel Brandt (Penn State) **
**Solar System: Steve Chesley (JPL) **
**Galaxies: Harry Ferguson (STScI) **
**Transients/variable stars: Shri Kulkarni (Caltech) **
**Large-scale Structure/BAO: Andrew Hamilton (Colorado) **
**Milky Way Structure: Connie Rockosi (UCSC)**
** ****Strong gravitational lensing: Phil Marshall (UCSB)**

*171 signed on already, from member *
*institutions and project team.*

## LSST optical design has a 3.5o FOV, 8.4m

**54**

**64cm focal plane**

**3 refractive **
**lenses**

**Primary**

**Tertiary**

**Secondary**

**LSST optical design has a 3.5****o**** FOV, 8.4m**
**primary, <0.2 arcsec PSF from ****l****=320-1050nm**

## Mirror Designs

**Mirror Designs**

- 8.4 Meters

- Primary Surface

- Tertiary Surface

- 0.9 M

***Unique Monolithic Mirror: Primary and Tertiary Surfaces Polished Into Single Substrate***
***Cast Borosilicate Design***

**Mirror Cell (Yellow)**

**Secondary Mirror **

**Baffle (Black)**

***Thin Meniscus Low Expansion Glass Design for Secondary Mirror***
***102 Support Actuators***

_***Secondary Mirror***_

_***Primary/Tertiary Mirror***_

## The telescope baseline design is complete

**Altitude over azimuth configuration**

**Camera and**
**Secondary assembly**

**Carrousel dome**

**Finite element**
**analysis**

## The LSST carrousel dome is 30m in diameter

**30 meters**

**The LSST carrousel dome is 30m in diameter**

## The LSST will be on El Penon peak in

**The LSST will be on El Penon peak in**
**Northern Chile in an NSF compound**

**1.5m photometric**
**calibration telescope**

## The LSST camera will have 3 gigapixelsin a 64cm diameter image plane

**The LSST camera will have 3 gigapixels****in a 64cm diameter image plane**

**Five Filters in stored location**

**L1 Lens**

**L2 Lens**

**Shutter**

**L1/L2 Housing**

**Camera Housing**

**L3 Lens**

**Raft Tower**

**Filter in light path**

**Notes:**
Contents:
	L1/L2 Housing
	Filter Changer and Carousel
	Shutter
	Assembly planning
	Packaging and internal interfaces
	Support structure and utilities
	External interfaces
	Access and servicing concepts

## Camera body with five filters and shutter

**Shutter**

**Filter Changer**

**Filter Carousel**

**Manual Changer access port**

**Back Flange**

**Filter Changer rail **

**Camera body with five filters and shutter**

## The LSST Focal Plane

**Guide Sensors (8 locations)**

**Wavefront Sensors (4 locations)**

**3.5 degree Field of View (634 mm diameter)**

_**Curvature Sensor Side View Configuration**_

**The LSST Focal Plane**

## The basic building block for the camera is the raft tower

**RAFT TOWER**

**Electronics**

**Raft Assembly**

**Flex Cable &**

**Electronics Cage**

**Thermal Straps**

**3 x 3 CCD Sensor Array**

**The basic building block for the ****camera is the raft tower**

## The LSST CCD Sensor

- 16 segments/CCD200 CCDs total3200 Total Outputs

## LSST Data Management Model

** **

_**Applications**_** ******** Science**
**     **Image processing, database queries, ...

_**Middleware**_** ******** Interface wrapper**
**    **Device drivers, system management,...

_**Infrastructure**_** ******** Hardware**
**     **Computers, disks, data links, ,,,

_**LSST Data Management Model**_

**LSST generates 6GB of raw data every 15 seconds **
**that must be calibrated, processed, cataloged, **
**indexed, and queried, etc. often in real time **

**The LSST Data Management **

## Data Management is a major part of the LSST mission

**The LSSTC partnership has DOE national labs (LLNL, SLAC, BNL), NSF centers (NCSA/UI-UC), US industry (Google, Inc.) and academic centers (Caltech, Stanford, Harvard) to create and operate a World-Class data management center**

## LSST imaging & operations simulations

- Sheared HDF raytraced +
- perturbation + atmosphere +
- wind + optics + pixel

- LSST Operations, including real weather data: coverage + depth

**Performance verification using Subaru 15 sec imaging**

## Project Management Status

**Reference Design complete**
**Full WBS with dictionary and task breakdown**
**Task-based estimate complete **
**Integrated cost/schedule complete**
**NSF MREFC proposal for submission ~Dec’06**
**NSF Concept Design Review planned in FY07**
**DOE CD-1 review planned in FY08**

## Timeline and budget for the LSST

*Commissioning*

*Operations*

**Timeline and budget for the LSST**

***FY-06       2007      2008       2009     2010       2011      2012     2013       2014      2015  ***

*Design and Development*

*Submit NSF MREFC Proposal*

*NSF and CD-2a funding begins *

*First light*

* **51 months*

*CD-0*

*(and early procurement)*

***Fiscal ***
***Years***

*CD-1*

##  Why Now?

**Broad science community interest**
**Synergy with 2013- multi-wavelength facilities**
**Multiple endorsements**
**Systematic risks addressed**
**Technically ready**

## Q&A slides

## DE Science Drives Short Exposures  

***Weak lensing requires exquisite control of shape systematics. ***
***One needs hundreds of exposures per filter per sky patch for ***_***chopping.***_
***Short exposures allow us to optimally weight.***
***Many exposures with sky rotated on detector permit another chop.***
***These require high etendue and short exposures.***

## Near Earth Objects

**Near Earth Objects**

**Inventory of solar system is incomplete**
**LSST would get orbits of nearly all NEOs**
**    ****larger than 140m (per congressional mandate)**
**Demanding project: requires mapping the sky down to 24****th**** magnitude every few days, individual exposures not to exceed 15 sec**
**Uses same sky tiling cadence optimal for dark energy**
**  **

## Difference imaging

**Deep Lens Survey**

## Full sampling improves linking

- per visit

**LSST baseline cadence**
**using r band data only**

- NASA NEO whitepaper

## Formation of our Galaxy and Group

- SDSS

- LSST

## Optical flashes

- ?

**Deep Lens Survey**

**difference**

## LSST will use existing NSF-funded fiber optic networks

- Cerro
- Pachon

- La
- Serena

**LSST will use existing NSF-funded fiber optic networks**

**Typical data rate**
**required ~2GB/sec**

**Notes:**
We have quotes for all major links and have active collaboration discussions with South American research communities and industries (e.g. mining) to pool demand to lower costs further.