# Presentation: YZOIIW3V6LACDH5BKHIEJVIOLXLRY7XH

## VO-GCN: A New Network for Astronomical Events

- Roy Williams
- Andrew Drake
- California Institute of Technology
- Rob Seaman
- Phil Warner
- NOAO, Tucson
- Scott Barthelmy
- NASA Goddard

- 1604 image of Cas A

## Transient Sources in the Sky

- Satellites (10000" per hour)
- Near Earth Objects (3000" per hour)
- Main Belt Asteroids (10" per hour)
- Trans-Neptunians (1" per hour)
- Radial-velocity planet searching (10 - 100 pc)
- Planet transit searching (100 - 10000 pc)
- M-dwarf flares
- Microlensing + CV + novae (100000 pc)
- RR Lyrae in the galactic halo
- Extragalactic microlensing (10 Mpc)
- Supernovae, microquasars
- Gamma Ray Bursts, Blazars
*And ...... NOT YET THOUGHT OF ....?*

- Optical
- Radio
- Gravitational wave
- Neutrino
- TeV shower
- etc

## Supernova from NASA Catalina SurveyMay 5, 2008

## Human Event Reporting

- All human-based
- Data entry problems
- Multiple site monitoring

- ATEL

- CBAT

- SNfactories

- Panstars

## Human Event Reporting

- Write with quill pen
- Send by horse to Boston
- Transcribe data correctly
- Read and decide to follow-up
- Transcribe data correctly
- Write with quill pen
- ....etc etc
- But now too many transients for quill pen!

## NASA GCN (1997)robotic observation of transients for gamma ray bursts

- Fabulous Science!
- Optical counterpart
- Robots do the work
- Purpose built and grown
- Needs update!

- Swift

- Integral

- Milagro

- HETE

- GCN

## GCN is Fabulous!

- GCN Data packets
- Binary, brittle, hundreds of kinds
- GCN protocol
- Outgoing sockets, firewall problems
- Unclear how to scale
- Hub and spoke
- All events come through NASA Goddard

- ... butneeds update to grow scientifically

## VO-GCN is Evolution of GCN

- Clear roles in extensible, distributed network
-  Author, Publisher, Repository, Subscriber
- Int’l agreement on XML packet
- Not just bytes and message types
- Follow-ups published in the same framework
- Sophisticated coordinate systems
- Multiple transports: socket, RSS, HTML, KML
- Digital signature
- Semantics and ontology
- Orbital elements and light curves can be expressed
- External schema -- eg solar physics events
- Global identifiers

## VOEvent

- Describing,
- automating,
- transporting,
- persisting,
- querying,
- correlating,
- securing,
- sharing,
- naming,
- and displaying
- coherent threads of scientific monitoring of celestial transient alerts

## VO-GCN (2008)

- VO-GCN

- GCN

- Catalina Sky Survey
- Palomar-Quest Survey
- SDSS Supernova Survey
- OGLE microlensing
- ESSENCE supervovae
- LBNL supernova factory
- MOA
- Murchison Widefield ArraySNEWSATEL
**GLAST**

## VOEvent Int’l Network

- Caltech

- Exeter

- LANL

- NOAO

- SDSS SNe
- U Washington/Stanford

- Pairitel
- Berkeley

- Palomar P60
- Caltech

- Palomar-Quest
- Caltech

- Raptor
- LANL

- Liverpool Telescope
- La Palma

- UKIRT
- Hawaii

- Author
- Publisher
- Repository
- Relay
- Subscriber

- Faulkes
- Hawaii/Australia

- OGLE III
- Poland

- GCN
- NASA/GSFC

- Microlensing Survey
- Exeter

- CTIO/KPNO
-  surveys and ToO

## What is VOEvent

- Author, Publisher, Subscriber, Repository
- Information not Imperative
- Receiver must Decide
- “Look what I found”
- Follow-ups are other VOEvents
- Connected in citation graph
- Event aggregation and selection
- Personal subscription (what is above my horizon)
- Publish *and* subscribe
- LSST and Panstars on board
- Global identifiers
- Resolvable at any VO registry
- HTN robotic network
- Correlation science

## Delivery protocols

- Delivery protocols

- SocketHTMLKMLRSSXMPP (IM)SMS

## VOEvent Structure

- Who
- Publisher, Contact, etc
- Subscribers will use AuthorID to select
- WhereWhen (== IVOA STC)
- Can be simple eg RA, Dec, eg UTC
- Can be sophisticated, eg multiple frames, near objects, etc
- Orbital elements
- What
- Hierarchy of named parameters
- Units, Semantic type (UCD)
- References, Descriptions
- Light curves
- How
- How was the evidence gathered: camera, telescope, etc
- Why
- probability list of interpretation
- supernova, comet, asteroid, .....
- Citation
- Link to other VOEvent: Followup, Supercede, Retraction,
- Link to support data
- Signature

## Citation

- An event can cite another
- 		<Citations><EventID cite=”**followup**">   		   ivo://gcn.nasa/VOEvent#hete_389241a_20050808_230931	</EventID> </Citations>
- Observations can be federated by mutual citation

- followup

- followup

- followup

- observation

- event collection

## Distributed VO Registry

- Caltech

- NCSA

- STScI/JHU

- HEASARC

- Astrogrid

- CDS

- JapanVO

- Events resolvable through distributed VO registry
- (soon)

- ESO

- CfA

- NOAO

## Google Sky

## Google Sky

## UsageDelivering KML events to GSky

- Ten hits a second
- Serving event KML

## VO-GCN example: Swift and historical supernovae

## VO-GCN: Novae in M31

## CorrelationExample: Swift events and TeV gamma events

- Exploitation Challenge

## More Information

- _[Standards process](http://www.ivoa.net/Documents/latest/VOEvent.html)_
- _[http://voevent.org](http://www.ivoa.net/Documents/latest/VOEvent.html)_
- VOEventNet with multiple feeds
- _[http://voeventnet.caltech.edu/](http://www.ivoa.net/Documents/latest/VOEvent.html)_
- VO-GCN with historical event repository
- http://voevent.noao.edu/