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STAR
Rapid, intelligent, automated follow-up
Tim Naylor
Alasdair Allan
Eric Saunders
University of Exeter
Iain Steele
Dave Carter
Jason Etherton
Chris Mottram
Liverpool John Moores University
Tim Jenness
Frossie Economu
Andy Adamson
Joint Astronomy Centre, Hawaii
In Brief
•  eSTAR is software “glue” for
–  telescopes
–  databases
–  catalogues.
•  Automated programmes in response to events.
•  UKIRT, LT and Faulkes telescopes.
•  VOEvent, RTML & HTN protocols designed
around it.
•  Peer-to-peer; intelligent agents.
STAR
Scenario 1 – What was that?
•  02:11:03UT: shutter closes on an SSS image of
Centaurus.
•  02:12:45UT: VOEvent announcing discovery of a
new, bright object in the data.
•  02:13:00UT: Passes criteria in an event filter
working for IA.
•  02:14:06UT: In response to the IA’s request for
confirmation a small telescope slews to acquire
another image.
STAR
•  Whilst waiting the IA queries SIMBAD and
discovers there is no known variable at this point.
•  02:19:34UT: The new image confirms the object,
so the IA requests a spectrum from 4-m class
Telescope.
•  Whilst waiting, the IA pulls all the other available
data and papers.
•  02:34:50UT: The spectrum is odd, there hasn’t
been γ-ray burst but VISTA shows a very faint red
object, mentioned in a paper last year…
•  02:35:30: An astronomer is woken up.
STAR
Scenario 2 – The space
density of dwarf novae.
•  Similar absolute magnitude in outburst.
•  Every CCD field taken in the world is
compared with the best (local) sky survey.
•  Objects which brighten above fixed
magnitude (say 16th) compared with SIMBAD.
•  Known dwarf novae noted.
•  Historical data searched for new objects,
used to identify lightcurve type.
STAR
Space density of dwarf novae.
•  If cannot be classified, further
observations requested.
•  As lightcurve builds up, future
observations placed optimally.
•  Object finally catalogued.
•  Astronomer comes back from long
lunch break and writes paper.
STAR
What sort of variable?
•  Mines SIMBAD to find variable stars at this
location.
The γ-Ray Burst Programme
•  We use UKIRT to provide rapid follow-up to γ-ray
bursts.
•  GCNs translated into VOEvents. Filtered for events
meeting the pre-defined criteria for trigger.
•  IA Places observation block in UKIRT queue.
•  Then tells observer at telescope and Nial what its
done.
•  Speed entirely limited by hardware.
•  Best catch GRB 090423 z≈8.2 (Tanvir et al, 2009,
Nature 416, 1254).
STAR
The µ-lensing Programme
•  eSTAR has provided the “negotiation” services for UK
part of planet-hunting µ-lensing programme.
•  St. Andrews calculate ideal observations.
•  eSTAR negotiates best approximation.
•  Feeds back observations completed.
•  OGLE-2007-BLG-224 (Gould et al 2009, ApJ 698
L147)
•  OGLE-2006-BLG-109 (Gaudi et al 2008, Science 319
927).
STAR
Period searches and supernovae
•  Optimising period searches (Eric Saunders).
•  Place one observation
•  See if you get it
•  Place next observation
•  Observing supernovae before they go off!
•  Neutrino burst precedes collapse reaching
surface.
•  Use alert from neutrino observatories
•  Survey area with UKIRT
STAR
Why is this hard?
•  Given certain circumstances you can decide what
observations are needed.
•  Are you then going to request a telescope drops
everything and does it?
•  You need to negotiate with several telescopes.
•  Complex asynchronous process (robustness).
•  Need a negotiation language - RTML
•  And a protocol for the exchange.
•  Allan et al (2006, Astr. Nacht. 327, 744)
•  Ends in an observation going into queue. STAR
Unique ideas…
•  Basic architecture is intelligent agents which interact
with telescopes and databases. •  Three fundamental ideas behind the project which
makes it unique.
•  Expertise split between IAs (science) and
telescope agents (scheduling).
•  Treat telescopes and databases in a similar
manner, both being made available on the
Observational Grid.
•  The main user of the Grid should not be humans,
but autonomous intelligent software agents.
•  Resulting system has no master controller, new
resources and observing programmes easy to add. STAR
Intelligent Agents, the Glue
•  Loosely, an agent is a computational entity which •  Acts on behalf of another entity in an autonomous
fashion. •  Performs its actions with some level of proactivity
and/or responsiveness. •  Exhibits some level of the key attributes of learning,
co-operation and mobility.
STAR
But what are the triggers?
•  The surveys will generate VOEvents. •  All are sent and archived at backbone nodes
(Caltech, NOAO and Exeter).
•  Then require “sever side” filtering, before forwarding
to you (since expect millions per day).
•  VOEvent archive is mine-able.
•  Interpretations as well as events can be VOEvents.
STAR
The eSTAR network
The VO
Embedded
Agent
© Nik Szymanek
User Agents
Embedded
Agents
Alert
Filter
OGLE III
Alert
Filter
GCN
Gateway
Service
VOEvent Network
CREDIT: Roy Williams, Rob Seaman, Alasdair Allan, Andrew Drake, Robert White, Matthew Graham, Philip Warner
Conclusions
•  SSS follow-up is likely to be highly competitive and
highly political.
•  We (the UK) are not providing the events, to lead the
science we can
•  identify importance of events (filtering) and/or
•  obtain key observations. •  eSTAR is key as:
•  we have one of the three VOEvent nodes and
associated expertise; we can do our own filtering;
•  we have the only functioning generalised system
for carrying out follow-up. STAR