VOEventAn Information Infrastructure

for Immediate Astronomical Events

Roy Williamsroy@caltech.eduNVO co-director

IVOA working group VOEvent

• Define semantics of message– Draft document for discussion– Curation, Wherewhen, How, What, Hypothesis

• Start vocabulary– Based on UCD -- IVOA standard

• Work with Strasbourg experts

• Use existing schema where possible– IVOA, RTML, STC

• Buy-in from communities– GRB/Swift, RTML, LIGO, Raptor,– LSST, Palomar-Quest, PanStarrs,– etc etc

http://www.ivoa.net/twiki/bin/view/IVOA/IvoaVOEvent

Current systems

• Partial List• IAU telegrams• Gamma-ray Coordinate Network• Astronomer's telegram• Global Microlensing Array Network• ????

• Text-based• meaning human-based

• Email-based• all messages to all subscribers

Proposed system• Curation

• from IVOA curation schema, from Dublin Core

• When, Where• STC? Simple?

• How• instrument state

– different schema for different instruments– RTML

• What• exactly what was seen

– different schema for different instruments

• Hypothesis• probability list of:

– supernova, comet, asteroid, .....– how can we make this list?

Proposed system

• Event has ivo:// identifier• Citation• Keep it light -- no data in VOEvent-- use links

• Subscription/query• get only the events you want

– based on complex criteria

• crossmatch event libraries

• Transport fabric• for human: email, cellphone• for robot: web-service, auto-email

VOEvent: General Info

• Who is making this report?– From VORegistry

• Based on Dublin Core

Dublin Core

Title: A name given to the resource.

Creator: An entity primarily responsible for making the content of the resource.

Subject: A topic of the content of the resource.

Description: An account of the content of the resource.

Publisher: An entity responsible for making the resource available

Contributor: An entity responsible for making contributions to the content of the resource.

Date: A date of an event in the lifecycle of the resource.

Type: The nature or genre of the content of the resource.

Format: The physical or digital manifestation of the resource.

Identifier: An unambiguous reference to the resource within a given context.

Source: A Reference to a resource from which the present resource is derived.

Language: A language of the intellectual content of the resource.

Relation: A reference to a related resource.

Coverage: The extent or scope of the content of the resource.

Rights: Information about rights held in and over the resource.

VOEvent: Where and When

• Where in the sky and when?– Simple:

• RA, Dec in J2000 + Julian Day– Not good enough for precise positions

– Sophisticated• How to ease burden of interpretation• Space-Time Coordinates

– Where was the observer?– What about nutation?– What about surface of Mars?

VOEvent: How

• How was the event detected?– Instrument description: which is in there?

• “Used Gunn R filter”• “Used MySpecial filter”• Camera darks and flats files at http://….• “Dome didn’t open until 3am”

– Instrument-specific for accurate info

VOEvent: What was detected?

• Instrument independent– Magnitude increase– GW strain– Good candidate for UCD

• eg phot.color.Gunn (Color index in Gunn system)

• Instrument dependent– Mag increase in MyFilter– Trigger number 736 with SNR=6

VOEvent: Classification

• What do we think happened?– How to build ontology?

Event Vocabulary

• Astronomer’s telegram– Radio, Millimeter, Sub-Millimeter, Far-Infra-Red, Infra-Red, Optical, Ultra-Violet, X-ray,

Gamma Ray, >GeV– Request for Observations, A Comment, – AGN, Asteroids, Binaries, Black Holes, Comets, Cosmic Rays, Cataclysmic Variables,

Globular Clusters, Gamma-Ray Bursts, Meteors, Microlensing Events, Neutron Stars, Novae, Planets, Planets (minor), Pulsars, Quasars, Soft Gamma-ray Repeaters, Solar System Objects, The Sun, Supernovae, Supernova Remnants, Transients, Variables, Stars

• UCD– IR, UV, X-ray, gamma, mm, opt, radio– Each in categories

• em.line.Brgamma Bracket gamma line• em.UV.100-200nm Ultraviolet between 100 and 200 nm • em.X-ray.soft Soft X-ray

• IAU Telegram– Outbursts Of Unusual Variable Stars, Features On Planetary Surfaces

Unified Content Descriptors

• UCD is a “semantic type”src.orbital.eccentricity Orbit eccentricity meta.code.mime MIME type pos.gal.lon Longitude in galactic coordinates phys.at.crossSection Atomic cross-section

• Can be resolved by web service– to description, examples, etc

VORegistry as a model for

VOEvent?

Registry model

VOEventregistry

user user

alerter

alerterpublish

subscribe

get ID

user

query

Registry model

VOEventregistry VOEvent

registry

VOEventregistry

user user

alerter

alerter

publish

harvest

subscribe

user

query

Distributed Registry

Caltech

NCSA

STScI/JHU

HEASARC

Astrogrid

CDS

JapanVO

Registries as of Jan 05

ESO

CfA

NOAO

VO Registry

VORegistry

VOResourceSchemas and

instances

VOIdentifierivo://nvo.caltech/DPOSS#f123

Subscribeservice

registry

registry

Extension schemas

Harvest

Publish service

registry

Human via web form

Machine via web service

Query service

VO Identifiers

ivo://mydomain.com / mySkySurvey # file00037.fits

Authority ID• Registered with IVOA• Resolved by registry

Resource ID• Created by Authority• Resolved by registry

Record ID• Not known to registry

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