VOEvent
IVOA Interop
May 2006
Roy Williams
NVO.Caltech
..... and many others .....
1604 image of Cas A
Multiple Event Streams
Event Authors
Swift (Barthelmy)
HETE2 (Butler)
Robotic Telescopes
Integral (Djorgovski will consult)
Raptor (Vestrand/White)
SDSS supernova search (Becker/Masao)
KAIT (Fillipenko/Li)
KAIT (Fillipenko/Li)
Pairitel (Bloom)
Microlensing Planet Search (Gaudi)
Palomar P60 (Kulkarni)
Essence (Smith, Wood-Vesey)
Robonet (Steele)
Palomar-Quest (Djorgovski)
AAVSO (Price)
Pairitel (Bloom)
Raptor (Vestrand/White)
Panstars (Kaiser, Price)
Gemini (8 meter telescopes)
AAVSO (Price)
ROTSE (Akerlof)
XTE satellite (Remillard)
Prompt (Reichart)
Glast (E. Bloom)
CTIO Smarts (Cobb, Baylan)
Allen Telescope Array (Bower)
VOEvent Structure

Who
Publisher, Contact, etc
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Subscribers will use AuthorIVORN to select
WhereWhen (== STC)
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Can be simple eg RA, Dec, eg UTC
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Can be sophisticated, eg multiple frames, near objects, etc
What
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Hierarchy of named parameters
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Units, Semantic type (UCD)
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References, Descriptions
How
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How was the evidence gathered: camera, telescope, etc
Why
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probability list of interpretation
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Citation
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supernova, comet, asteroid, .....
Link to other VOEvent: Followup, Supercede, Retraction,
Link to support data
Reference
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Supporting material, eg lightcurve, image
<Who>
is the scientifically-responsible Author?
<Author>
<title>Rapid Telescope for Optical Response</title>
<shortName>Raptor</shortName>
<logoURL>http://www.raptor.lanl.gov/images/RAPTOR_patchLarge.jpg</logoURL>
<contactName>Robert White</contactName>
<contactEmail>rwhite@lanl.gov</contactEmail>
<contactPhone>+1 800 555 1212</contactPhone>
</Author>
or
<AuthorIVORN>ivo://raptor.lanl/organization</AuthorIVORN>
• An IVORN for an organization
• Easier for Subscribers to find Author
• Shorter packet
<What>
was actually observed
Parser can cast this Group
to class phot_pt
A time sequence of Rmagnitudes
<What>
<Group type="phot_pt" >
<Param name="mag1" ucd="phot.mag;em.opt.R" value="13.2" unit="mag" />
<Param name="epoch1" ucd="time.epoch" value="245523.12345" unit="day"/>
</Group>
<Group name=”gamma_flux">
<Param name="counts" value="73288" ucd="phot.count"/>
<Param name="peak" value="1310" ucd="arith.rate;phot.count"/>
</Group>
</What>
<Why>
do we think this happened?
Importance of the event observation
should I interrupt my telescope schedule?
Publisher thinks (prob=0.98) this is a
SN1a with given name
<Why importance="13.0" expires="1574-05-11T12:00:00">
<Inference probability=”0.98">
<Name>Tycho's Stella Nova</Name>
<Concept>SN Ia</Concept>
</Inference>
<Inference probability=”0.2" relation="associated” >
<Name>3C 10</Name>
<Concept>supernova remnant</Concept>
</Inference>
</Why>
Possibility this is associated with
object 3C10
<WhereWhen>
Standard STC
coordinate frame
Space-Time Coordinates
<WhereWhen>
<ObsDataLocation xmlns="http://www.ivoa.net/xml/STC/stc-v1.30.xsd" >
<ObservatoryLocation id="KPNO" xlink:type="simple"
xlink:href="ivo://STClib/Observatories#KPNO"/>
<ObservationLocation>
<AstroCoordSystem id="UTC-FK5-GEO" xlink:type="simple" xlink:href="ivo://STClib/CoordSys#UTC-FK5-GEO/>
<AstroCoords coord_system_id="UTC-FK5-GEO">
<Time unit="s">
<TimeInstant>
<ISOTime>2005-04-15T23:59:59</ISOTime>
</TimeInstant>
<Error>1.0</Error>
</Time>
<Position2D unit="deg">
<Value2>
<C1>148.88821</C1>
<C2>69.06529</C2>
</Value2>
<Error2Radius>0.03</Error2Radius>
</Position2D>
</AstroCoords
</ObservationLocation>
</ObsDataLocation>
</WhereWhen>
VOEventNet and eStar
OGLE III
GCN
NASA/GSFC
Poland
Liverpool Telescope
La Palma
SDSS SNe
U Washington/Stanford
Faulkes
Hawaii/Australia
Exeter
Palomar-Quest
Caltech
Caltech
LANL
Microlensing Survey
UKIRT
Exeter
Hawaii
NOAO
Palomar P60
Caltech
Raptor
Pairitel
LANL
Berkeley
CTIO/KPNO
surveys
Author
Publisher
Repository
Relay
Subscriber
VOEvent transport model
Author
Publisher
immediate
push
Subscriber
Repository
Aggegator
• digest (RSS)
• resolve
• query
client
Multiple authors, publishers, subscribers
Structured, semantically rich, for machine understanding
XML representation
Standard transports (web service, email, etc)
Standard global identifiers
Filter
VO Identifiers
Registry finds the VOEvent repository
Repository finds the specific event
Local ID
• Not known to registry
• Created by Publisher
• Known to event repository
• Publisher IVORN
• Resolved by registry
to find repositories
ivo://pq.nvo.caltech/VOEPublisher
delimiter
#
delimiter
Event IVORN (whole thing)
20050523c
Registry Usage for VOEvent
Client
Author
(science)
Subscribers
publish
event
1. Resolve identifier
ivo://publisherID#localID
Publisher
(identifier, signature)
4: Receive event
metadata
VO Global
Registry
2. Which repositories
have events
from this publisher?
store
event
Repository
3: Send
localID
Citation
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An event can cite another
<Citations><EventID cite=”followup">
ivo://gcn.nasa/VOEvent#hete_389241a_20050808_230931
</EventID> </Citations>
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Observations can be federated by mutual
citation
observation
followup
followup
followup
event collection
Control

Author A sends event E to Subscriber S

Subscriber software decides on action....
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S can followup everything from A
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S can followup if importance > threshold

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S can followup if prob(Supernova) > threshhold

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(importance is part of every event)
<Why> section has hypothesis, concept, association
S can examine the parameters, images, lightcurves

<What> section is observations
Transport
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Querying and web pages as usual
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client connects to server
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RSS polling is like this
Subscription
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One of
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Client keeps open socket to server
Server keeps open connection to client (GCN model)
Subscriber protocol
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Jabber/XMPP -- popular IM protocol
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Home made -- “TCP Vanilla”
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Java Messaging
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One-way SOAP (port 80)
VOEventNet: a Rapid-Response Telescope Grid
Palomar-Quest
PQ next-day
pipelines
baseline
sky
Raptor
Palomar 60”
catalog
PQ Event
Factory
Event Synthesis
Engine
VOEvent
database
VOEventNet
Pairitel
known
Variables
known
asteroids
2MASS
SDSS
remote archives
eStar
VOEvent Structure
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Event has ivo:// identifier (the IVORN)
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Citation connects events
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Citation
Keep it light -- no data in VOEvent-- use links
Discovery, Followup, Supercede, Join, Predict
Subscription / query / digest (RSS)
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get only the events you want
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based on complex criteria
based on publisher
crossmatch event libraries
Transport fabric
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for human: email, cellphone, IM
for robot: IM, web-service, auto-email, socket
VOEvent Schema 1.1
Last major schema change?
End of the Beginning of VOEvent.....
Ivorn for IVOA identifiers
ivorn

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International Virtual Observatory Resource
Name
Can be recognized by ivo:// at start
in place of id
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(collides with XML usage of this attribute)
MIME type
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VOEvents should be
application/xml+voevent
Roles

Author
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Publisher
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XML Responsibility
Creates unique IVORN
Subscription interface
Repository
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Scientific Responsibility
Metadata same as IVOA Organization
title, shortName, description, logo,
contact (Name, Email, Phone), Contributor
Resolves IVORNs
Query interface (SEAP)
Relays, Filters, and Brokers
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Combinations of basic roles
<Who> now means Author
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The <Who> element how has
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AuthorIVORN in place of PublisherID
Choice of explicit or implicit metadata
VOEvent and Registry
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Author may be registered
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may be cited by IVORN in VOEvent packet
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Publisher is registered
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Saves typing
Easier for subscriber to pick known authors
equivalence of <Who> with IVOA Organization
List of authors, How to subscribe
Repository is registered

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Which publishers are kept
IVORN resolution. Query interface
Queries for VO Registry
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Tell me about this Author
Tell me about this Publisher
Tell me about this Repository
Which Publisher has this Author?
Which Repository has this Publisher?
VOEvent identifier (IVORN)
1. Given an event ivorn:
ivo://nvo.caltech/voe-publisher#666
2. parse into:

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publisher ivorn:
and local key:
ivo://nvo.caltech/voe-publisher
666
3. Ask VO registry:
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Which repository has this publisher?
4. Use query interface on repository:
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Tell me about event 666
STC adopted
(No more mealy-mouthed nonsense about RA and Dec elements)
pseudocode
Let x = WhereWhen/ObsDataLocation/
ObservationLocation/AstroCoords
If x[@coord_system_id=‘FK5-UTC-TOPO’] then
Let Time = x/Time/TimeInstant/ISOTime
Let RA = x/Position2D/Value2/C1
Let Dec = x/Position2D/Value2/C2
<WhereWhen>
<ObsDataLocation
xmlns="http://www.ivoa.net/xml/STC/stc-v1.30.xsd"
xmlns:xlink="http://www.w3.org/1999/xlink">
<ObservatoryLocation id=”KPNO" xlink:type="simple"
xlink:href="ivo://STClib/Observatories#KPNO"/>
<ObservationLocation>
<AstroCoordSystem id="FK5-UTC-TOPO"/>
<AstroCoords coord_system_id="FK5-UTC-TOPO">
<Time unit="s">
<TimeInstant>
<ISOTime>2005-04-15T23:59:59</ISOTime>
</TimeInstant>
<Error>1.0</Error>
</Time>
<Position2D unit="deg">
<Value2>
<C1>148.88821</C1>
<C2>69.06529</C2>
</Value2>
<Error2Radius>0.03</Error2Radius>
</Position2D>
</AstroCoords>
</ObservationLocation>
</ObsDataLocation>
</WhereWhen>
Concept
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The <Concept> element now holds
controlled vocabulary
For draft (IVOA Semantics WG), see
http://www.ivoa.net/twiki/bin/view/IVOA/VOEventVocabulary