IVOA Time Domain Interest Group
Working Group Chair: John Swinbank
Vice Chair: DaveMorris
Chairs Emeritus: Roy Williams
, Rob Seaman
, Matthew Graham
Vice Chairs Emeritus: Alasdair Allan
, Roy Williams
, John Swinbank
, Mike Fitzpatrick
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.
- 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 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.
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.
provides a web-based interface for exploring and collating VOEvents and defining personalised event alert schemes.
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 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.
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 1.1 protocol for subscriber, publisher, and broker-to-broker operations. The Dakota tools are written in portable C#.
- 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.
, 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
Time Series Data
is an XML format, developed outwith the IVOA, for representing time-series data.
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.
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.
- IVOA InterOp - TDIG Session, Stellenbosch, South Africa, 11 May 2016
- VAO All-hands meeting requires login - Charlottesville, VA, Sep 30 - Oct 1, 2010
- SPIE AT&I, especially Obs. Ops. session 4, Orlando, May 24 - 31, 2006
- VOEvent session at the IVOA Interoperability Meeting in Madrid, October 6 - 7, 2005
- VOEvent session at the IVOA Interoperability Meeting in Kyoto, May 16-20, 2005
Gamma-ray Burst Coordinate Network (GCN)
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
STAR Project is now defunct.
Discussion leading up to the VOEvent Recommendation