IVOA Time Domain Interest Group

Working Group Chair: Judy Racusin

Vice Chair: Pierre Fernique

Chairs Emeritus: Ada Nebot, Roy Williams, Rob Seaman, Matthew Graham, John Swinbank, Rafael Martinez-Galarza

Vice Chairs Emeritus: Alasdair Allan, Roy Williams, John Swinbank, Mike Fitzpatrick, Dave Morris

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Charter

The time domain is the emerging field of astronomical research, as recognized in the European ASTRONET and 2010 US National Research Council Decadal Survey of Astronomy and Astrophysics. Planned facilities for the next decade and beyond, both ground-based, such as the LSST and SKA, and space-based, such as CHEOPS, EChO and PLATO, will revolutionize our understanding of the universe with nightly searches of large swathes of sky for changing objects and networks of robotic telescopes ready to follow up in greater detail selected interesting sources. This will impact essentially every area of astronomy, from the Solar System to cosmology, and from stellar evolution to extreme relativistic phenomena, making it a very rich area for scientific exploration and discovery, and extending beyond the traditional electromagnetic spectrum into neutrino and gravitational wave astronomy. Moreover, many interesting phenomena, e.g., supernovae and other types of cosmic explosions, can only be studied in the time domain. The challenges lie in the automated distribution, processing, classification, and archiving of vast streams of triggers. The VO is well-placed to support and facilitate research in this area.

The IVOA Time Domain Interest Group has evolved from the IVOA VOEvent Working Group recognizing that the mechanics of celestial event notification are now broadly resolved within the VO but that broader representation of the emerging time domain community has become necessary.

It will:

• Provide a forum for discussing time domain specific issues in a VO context.
• Contribute to other IVOA working groups to ensure that time domain specific requirements are included.
• Incorporate standard approaches defined in these groups when designing and implementing services on time domain archives.
• Define standard services relevant for time domain archives.
• Promote development of services for comparing theoretical results to observations and vice versa.
• Define relevant milestones and assign specific tasks to interested parties.

VOEvent

VOEvent defines the content and meaning of a standard information packet for representing, transmitting, publishing and archiving information about a transient celestial event, with the implication that timely follow-up is of interest. VOEvent 2.0 was published as an IVOA Recommendation on 11 July 2011. The VOEvent 2.0 wiki, which was used to discuss the evolution of the standard, is still available.

Introductory Material

A tutorial introduction, based on material prepared for Hotwiring the Transient Universe IV in May 2015, is available.

The VOEvent book, "Hotwiring the Transient Universe", provides an introduction to the VOEvent system and related infrastructure. It is available in printed form from Lulu. A Kindle version is also available: do a "download file as" and drag to the documents directory on your Kindle via USB.

SkyAlert provides a web-based interface for exploring and collating VOEvents and defining personalised event alert schemes.

Dakota and Comet provide tools for connecting to high-speed TCP streams of VOEvents.

NASA Gamma-ray Coordinates Network provides a VOEvent stream of GRB and transient notices, including example source code for tools to receive messages.

VOEvent Transport

VOEvent is deliberately transport-agnostic. However, the VOEvent Transport Protocol (VTP) may be used to distribute streams of VOEvents across the internet with a relatively low latency. The following "brokers" provide access to such streams. A tool such as Dakota or Comet, below, is required to subscribe.

Address	Port	Organization	Accessibility	Comments
voevent.dc3.com	8099	DC3 Dreams	Public	Dakota broker "home" site, feeds GCN, 4 Pi Sky, LOFAR, others.
voevent.swinbank.org	8099	Comet	Public	Comet broker "home" site; deploys the latest pre-release.
voevent.transientskp.org	8099	LOFAR/Univ. Amsterdam	Public
envoy5.cacr.caltech.edu	8099	Skyalert/Caltech	Public	CRTS etc. Offline as of 2014-07-08.
voevent.4pisky.org	8099	4 Pi Sky	Public
209.208.78.170	8099	NASA GCN	Public	Only GCN events; VOEvent 1.1.
50.116.49.68	8099	NASA GCN	Public	Only GCN events; VOEvent 1.1.
68.169.57.253	8099	NASA GCN	Public	Only GCN events; VOEvent 2.0.
45.58.43.186	8099	NASA GCN	Public	Only GCN events; VOEvent 2.0.

Tools and Libraries

Since VOEvents are XML documents, they can be manipulated with a wide range of standard tools. In addition, the following libraries and tools may be useful.

Generating, Reading and Manipulating VOEvents

• VOEventLib is a Python library for working with VOEvent documents.
• voevent-parse is a lightweight Python library for parsing, manipulating, and generating VOEvents.

Working with the VOEvent Transport Protocol

• The Dakota VOEvent Tools are a cross-platform, open source set of tools which fully implement the VOEvent Transport protocol for subscriber/listener, publisher, and broker operations, as well as strict VOEvent 2.0 packet validation. Dakota includes a fully functional broker. The Dakota tools are written in portable C# and are open source.
• Comet is a Python implementation of the VOEvent Transport Protocol. It is capable of receiving events either by subscribing to one or more remote brokers or by direct connection from authors, and can then both process those events locally and forward them to its own subscribers. In addition, Comet provides a tool for publishing VOEvents to a remote broker.
• PyGCN is a Python-based client that anonymously listens for VOEvent format notices from the NASA Gamma-ray Coordinates Network over the VOEvent Transport Protocol.

VOEvent Databases

voeventdb, run by the 4 Pi Sky project, provides a REST interface to a database of VOEvents. See their tutorial for examples of what this makes possible.

VOEventStream: Metadata for Collections of Events

VOEventStream-0.2.html

Shanghai interop 2017, discussion session for VOEvent

Time Series Data

What is "Time Series Data"? It is a temporal sequence of measurements containing a time coordinate and a flux (or similar - magnitude) / RV / position / polarisation / number of spots / spectra / images,...

Science use Cases for Time Series

• Science use Cases for Time Series from the CSP
• New science cases have been presented at the Shanghai 2017 meeting.

TIMESYS: annotating time in VOTables

• Proposed TIMESYS element in VOTable for minimum metadata
• VOTable including the TIMESYS element

ST-MOCs: connecting space & time coverages

• ST-MOC Note
• Test & Demo
• ST-MOCs now in mocpy
• P8-3.pdf
• T-MOC Notebook

Astropy and TimeSeries

• astropy-timeseries package
  • Time class
  • QTable
• APE 9: Timeseries object for Astropy
• Give feedback on API

Some other relevant documents concerning Time Series

• IVOA note for Time Series Cube DM
• Note Time Series Cube Data Model V1.0: 2017-02-05
• Discussion on Time Series Cube DM Note
• SimpleTimeseries

InterOps presentations

Virtual 2021 May

• Opening
• Presentations

Virtual Nov 2020

• Opening

Virtual May 2020

• Opening

Groningen 2019

• Opening

Paris 2019

• Presentations
• Summary and Next steps

College Park 2018

• Presentations
• Summary

Victoria 2018

• Presentations
• Summary

Santiago 2017

• Program and presentations under http://wiki.ivoa.net/twiki/bin/view/IVOA/InterOpOct2017TDIG
• Summary of presentations and discussions

Shanghai 2017

• Presentations
• Summary of presentations
• After this meeting it has been proposed to form a task force team DAL/DM/TDIG. See discussion

Other meetings

VOEvent and GCN discussion 20 Sep 2022

• Minutes by Tess Jaffe

Strasbourg 2017 Meeting

• Agenda
• Notes and summary
• Volute repository for data samples and standardized VOTables
• Minimal requirements for Time Series Data Discovery and Access

Strasbourg 2018 Meeting

Goal: work on the Time Series model and annotation. Summary of the meeting:

• We have converged to one unique model for simple time series. See UML
• We started from Gaia requirements
• Different serialisations and annotations on VOTables are proposed:
  • VODML
  • VODML-Lite
  • Utypes
• TIMESYS annotation in VOTables
• We have a roadmap to provide a working prototype by end of 2019.
  • Examples based on Gaia DR2 light-curves are being built (deadline mid September)
  • These need to be properly tested by data providers and clients (deadline to start the testing loop end September)
  • Present results as a note (deadline end of October) and discuss at the next interop (mid November)
• Detailed notes of the meeting can be found here

2020 time series proposal

A new proposal to meet a specific set of requirements Time Series 2020.

Some relevant missions concerning Time Series

• gaia
• Pan-STARRS
• Intermediate Palomar Transient Factory
• Zwicky Transient Facility (ZTF)
• The PTF and ZTF Science Data Systems are housed at IPAC:
  • Light-Curves http://www.ptf.caltech.edu/page/lcgui
  • Example for a RR-Lyrae
  • Time Series Tool
• Large Synoptic Survey Telescope
• VST Kepler2 follow-up observations
• Next Generation Transit Survey
• PESSTO Transient Classifications
• Transiting Exoplanet Survey Satellite
• DASCH

Mailing List

All interested parties are welcome to join the mailing list: please use it not only suggest and discuss technical proposals, but also to explore how the TDIG can best engage with your particular science goals.

• List information and subscription
• Archive

Note that the volume of "spam" subscription requests received means that legitimate ones can sometimes get lost: if you don't receive a timely receipt of your subscription, please accept our apologies and try again or contact the TDIG chair or vice chair for help.

Past Events

• AstroInformatics

• School of Statistics for Astrophysics 2019 (Stat4Astro): Variability and Time Series Analysis

• Astrostatistics School

• The 1st Donglu Astrophysics Forum - The era of large-scale sky surveys: Near field cosmology and time domain science

• EWASS 2019: S1 Exploring the time-domain phase space from current surveys to LSST

• Hot-wiring the Transient Universe VI

• The ninth OPTICON Gaia Science Alerts workshop

• Microlensing Data Challenge, submission deadline: October 31 2018

• Time Domain Astronomy - A High Energy View, 13-15 June 2018, Madrid, Spain

• Transient Sky in 2020, 1st week of June 2018, France

• Strasbourg Time Series Data Meeting, 5-6 December, Strasbourg, France.

• Transient Sky in 2020, 20-22 June 2017, Paris, France.

• Southern Horizons in Time-Domain Astronomy IAU Symposium 339, 13-17 November 2017, Stellenbosch, South Africa.

• ASTERICS workshop on Radio - γ: Transient Alert Mechanisms, September 26-28, Amsterdam, Netherlands

• IVOA InterOp - TDIG Sessions, Shanghai, China, 15-19 May 2017

• Asterics Time Domain day and Tech Forum - Minutes of TimeSeries hackathon sessionl, Strasbourg, 21-23 March 2017

• Hot-wiring the Transient Universe V, Villanova University, October 10-14, 2016

• IVOA InterOp - TDIG Session, Stellenbosch, South Africa, 11 May 2016

• Hot-wiring the Transient Universe IV, Santa Barbara, CA, May 12-15, 2015

• IVOA InterOp - TDIG Session, Madrid, Spain, 22 May 2014

• Hot-wiring the Transient Universe III, Santa Fe, NM, Nov 13-15, 2013

• IVOA InterOp - TDIG Session, Hawaii, USA, 26 Sep 2013

• IAU Symposium, New Horizons in Time Domain Astronomy - Oxford, UK, Sep 19-23, 2011

• ADASS time domain tutorial Techniques in Time Domain Astronomy - Boston, MA, Nov 7, 2010 - 4:00-6:00 pm

• VAO All-hands meeting requires login - Charlottesville, VA, Sep 30 - Oct 1, 2010

• LSST All-hands meeting - Tucson, AZ, August 9-13, 2010

• SPIE Astronomical Telescopes & Instrumentation - Observatory Operations III - San Diego, CA, June 27 - July 2, 2010

• IVOA InterOp - VOEvent sessions, Victoria, BC, Canada, May 17-21, 2010

• Eventful Universe - Tucson, AZ, March 17-20, 2010

• IVOA InterOp - VOEvent session, Baltimore, MD, Nov 8-12, 2009

• Hotwiring the Transient Universe II, UC Santa Cruz, 26-30 April 2009

• ADASS XVIII BOF, Quebec City, Canada, November 2-5, 2008

• IVOA InterOp - VOEvent sessions, Baltimore, MD, October 27-31, 2008

• Fourth HTN Workshop, Santa Barbara, CA, July 30 - August 6, 2008

• IVOA InterOp - VOEvent/Semantics sessions, Trieste, Italy, May 19-23, 2008

• NASA AISR Investigator Workshop, College Park, MD, May 5-7, 2008

• Practical Semantic Astronomy Workshop, Pasadena, CA, February 18-21, 2008

• IVOA InterOp - VOEvent session, Cambridge, UK September 27-28, 2007

• ADASS XVII BoF(s), London, UK September 23-26, 2007

• Hot-wiring the Transient Universe: A Joint VOEvent & HTN Workshop, Tucson, AZ, June 4 - 7, 2007

• ADASS Autonomous BoF, Tucson, Arizona October 16, 2006

• Second HTN Workshop, Göttingen, Germany July 23 - 26, 2006

• SPIE AT&I, especially Obs. Ops. session 4, Orlando, May 24 - 31, 2006

• IVOA Interop, Victoria, May 15 - 22, 2006

• First VOEventNet Workshop, Berkeley, May 3 - 5, 2006

• Transient Universe 2006, Santa Barbara, March 13 - 14, 2006

• The Second VOEvent Workshop, Tucson, December 5 - 6, 2005

• VOEvent session at the IVOA Interoperability Meeting in Madrid, October 6 - 7, 2005

• ADASS VOEvent BoF, October 3, 2005

• NVO Summer School Demo, September 14, 2005

• HTN Workshop, July 18 - 21, 2005

• Joint session with UCD group at the IVOA Interoperability Meeting in Kyoto, May 16-20, 2005

• VOEvent session at the IVOA Interoperability Meeting in Kyoto, May 16-20, 2005

• VOEvent Workshop, April 13-14, 2005 - Report

Links

Gamma-ray Burst Coordinate Network (GCN)

Astronomer's Telegram

RTML - Remote Telescope Markup Language and Twiki here

Real Time Virtual Observatory

Space-Time Coordinate Metadata for the Virtual Observatory (STC)

Unified Content Descriptors, and more here

Resource Metdata for the Virtual Observatory

Pairitel Project

The eSTAR Project is now defunct.

AAVSO

Discussion leading up to the VOEvent Recommendation

• VOEventRFC

• VOEvent.html: VOEvent v1.11, IVOA Recommendation

• VOEvent_v1.1.html: VOEvent v1.1, IVOA Proposed Recommendation

• VOEvent-v1.0.xsd: VOEvent v1.0 schema

• VOEvent-v1.0-schema.pdf: Model diagram of the v1.0 schema

• VOEvent-v1.0.html: VOEvent v1.0 specification

• VOEvent_transport_060412.html: VOEvent transport, early draft

• VOEventService-0.2.html:

• VOEventService-0.2.html:

• SEAP-v0.1.doc: First write-up of SEAP

• voevent_v2.html: initial VOEvent v2.0 working draft