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Roy Williams Caltech and US National Virtual Observatory

VOEvent An Information Infrastructure for Immediate Astronomical Events a Working Group of the International Virtual Observatory Alliance. Roy Williams Caltech and US National Virtual Observatory. 1604 image of Cas A. Event networks today. subscribe. GCN service. user. user.

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Roy Williams Caltech and US National Virtual Observatory

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  1. VOEventAn Information Infrastructurefor Immediate Astronomical Eventsa Working Group of theInternational Virtual Observatory Alliance Roy WilliamsCaltech andUS National Virtual Observatory 1604 image of Cas A

  2. Event networks today subscribe GCN service user user Other providers? Extensibility? Interoperability? Eg LIGO, Pannstarrs, Palomar-Quest, SNEWS, LSST, Raptor, etc? Transport is handmade publish subscribe IAU telegrams Astronomers Telegram Etc etc observer user user Natural language -- not computer usable

  3. VOEvent transport model publish observer VOEvent database harvest VOEvent database VOEvent database query observer subscribe digest (RSS) user user user Structured, semantically rich, for machine understanding XML representation Standard transports Standard global identifiers

  4. Pasadena VOEvent WorkshopApril 13/14 Alasdair Allan Exeter, UK eStars Tim Axelrod LSST LSST Scott Barthelmy NASA GCN Vasily Belokurov Cambridge, UK Milan Bogosavljevic Caltech Palomar-Quest Joshua Bloom Berkeley Paritel George Djorgovski Caltech Palomar-Quest Andrew Drake Princeton MACHO Derek Fox Caltech Astronomer’s Telegram Matthew Graham Caltech Palomar-Quest Frederic Hessman Göttingen RTML, MONET Ashish Mahabal Caltech Palomar-Quest Szabolcs Marka Columbia LIGO Carl Pennypacker LBNL Hands On Universe Paul Price Hawaii PanStarrs Arnold Rots CfA Harvard Rob Seaman NOAO Tucson Kate Scholberg Duke SNEWS, MACRO Tom Vestrand LANL Raptor Robert White LANL Raptor Roy Williams Caltech Ramon Williamson NCSA Przemyslaw Wozniak LANL Raptor

  5. VOEvent Structure • Who • Publisher, Contact, etc • From RTML schema? • WhereWhen • Can be simple eg RA, Dec, eg UTC • Can be sophisticated, eg multiple frames, near objects, etc • What • Hierarchy of named parameters • Units, Semantic type • How • How was the evidence gathered: camera, telescope, etc • Why • probability list of interpretation • supernova, comet, asteroid, ..... • Citation • Link to other VOEvent: Followup, Supercede, Retraction, • Link to support data

  6. VOEvent Structure • Event has ivo:// identifier • Citation • Keep it light -- no data in VOEvent-- use links • Subscription / query / digest (RSS) • get only the events you want • based on complex criteria • based on publisher • crossmatch event libraries • Transport fabric • for human: email, cellphone • for robot: web-service, auto-email, socket

  7. Who Expect users to select on publisher Schema taken from RTML…. <Who> <Publisher> ivo://raptor.lanl/ </Publisher> <Date>2005-04-15T14:34:16</Date> <Contact PI="true"> <Name>Robert White</Name> <Institution>LANL</Institution> <Address> Los Alamos National Laboratory PO Box 1663 ISR-1, MS B244 Los Alamos, NM  87545 </Address> <Telephone>+1-505-665-3025</Telephone> <Email>rwhite@lanl.gov</Email> </Contact> </Who>

  8. WhereWhen • 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?

  9. WhereWhenUse IVOA Space-Time coordinate standard <WhereWhen> <stc:ObservationLocation> <crd:AstroCoords coord_system_id="FK5-UTC"> <crd:Time unit="s"> <crd:TimeInstant> <crd:Timescale>UTC</crd:Timescale> <crd:ISOTime>2005-04-15T23:59:59</crd:ISOTime> </crd:TimeInstant> </crd:Time> <crd:Position2D unit="deg"> <crd:Value2>148.888 69.065</crd:Value2> <crd:Error1Circle><crd:Size>0.1</crd:Size></crd:Error1Circle> </crd:Position2D> </crd:AstroCoords> </stc:ObservationLocation> </WhereWhen>

  10. What A set of named parameters, with unit, semantic type, grouping From a GCN notice GRB_INTEN: 73288 [cnts] Peak=1310 [cnts/sec] which would be expressed in VOEvent:What <Group name="GRB_INTEN"> <Param name="cnts" value="73288" ucd="phot.count" /> <Param name="peak" value="1310” ucd="arith.rate;phot.count" /> </Group>

  11. 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.crossSectionAtomic cross-section • Can be resolved by web service • to description, examples, etc

  12. How <How> <Instrument> <Name>Raptor AB</Name> <Location>Los Alamos</Location> <Ref uri="http://www.raptor.lanl.gov/documents/phase_zero.rtml" type="rtml" /> </Instrument> </How> Observation described by RTML document

  13. HowWhat do we THINK is true <Why> <Classification probability=”0.30"> <Class>Fast Orphan Optical Transient</Class> </Classification> <Classification probability=”0.75 type=“association”> <Identity>NGC 1234</Identity> </Classification> <Importance>1500</Importance> </Why>

  14. VO Identifiers • Authority ID • Registered with IVOA • Resolved by registry • Resource ID • Resolved by registryto specific VOEvent database • Record ID • Not known to registry • Known to event database ivo://pq.nvo.caltech / VOEventServer # 20050523c delimiter delimiter

  15. Distributed IVOA Registry pq.nvo.caltech Astrogrid CfA NCSA CDS ESO STScI/JHU NOAO ESAC Caltech HEASARC JapanVO NRAO I want event ivo://pq.nvo.caltech.edu -- talk to ANY IVOA registry IVOA registries as of Apr 05 Can resolve VOEvent identifier Redirect to specific VOEvent Database that has it

  16. <VOEvent type="update" id="ivo://raptor.lanl/235649409/sn2005k" xmlns:stc="http://www.ivoa.net/xml/STC/stc-v1.20.xsd" xmlns:crd="http://www.ivoa.net/xml/STC/STCcoords/v1.20"> <Who> <Publisher> ivo://raptor.lanl/ </Publisher> <Date>2005-04-15T14:34:16</Date> </Who> <WhereWhen> <stc:ObservationLocation> <crd:AstroCoords coord_system_id="FK5-UTC"> <crd:Time unit="s"> <crd:TimeInstant> <crd:Timescale>UTC</crd:Timescale> <crd:ISOTime>2005-04-15T23:59:59</crd:ISOTime> </crd:TimeInstant> </crd:Time> <crd:Position2D unit="deg"> <crd:Value2>148.888 69.065</crd:Value2> <crd:Error1Circle><crd:Size>0.1</crd:Size></crd:Error1Circle> </crd:Position2D> </crd:AstroCoords> </stc:ObservationLocation> </WhereWhen> <What> <Param name="magnitude" ucd="phot.mag:em.opt.R" value="13.2" /> </What> <Why> <Classification probability="30" units="percent" type="ot"> Fast Orphan Optical Transient </Classification> </Why> </VOEvent> Simplest VOEvent

  17. Issues Initial Implementation Caltech/Berkeley/LANL/UK? as next generation GCN? Transport protocols Subscription, Digest (RSS), Query Socket, Web service, email Identifiers and authorities obtaining an identifer and its persistence name resolvers Authentication of trusted publishers Aggregating related events

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