VOConcepts @ VOEvent 2005-12-05T13:30:00+8, Tucson

VOConcepts, the IVOA Standard

Vocabulary, VOEvent & You

Frederic V. “Rick” HessmanGeorg-August-Universität Göttingen

VOConcepts @ VOEvent 2005-12-05T13:30:00+8, Tucson

History• Misc. attempts at a general-purpose astronomical ontologies, e.g.– 2002 AstroGrid meeting @ Edinburgh– Talbot/U.Ottawa (http://www.site.uottawa.ca/astronomy)

– Shaya/GSFC (http://archive.astro.umd.edu/ont/)

– CDS/IVOA UCDs for VOTable– 2005 local meeting @ CDS/Strasbourg

• VOEvent I @ CalTech– Response/description of events incomplete/error prone without common object vocabulary (“SN” or “supernova”? “Unknown visual flash” or “Orphan optical transient” )

– Can’t always depend upon “common usage”, computers stupid

VOConcepts @ VOEvent 2005-12-05T13:30:00+8, Tucson

RTML 3.x• Similar problem to VOEvent: need standardized

classification of targets in an anonymous observation request

• <TargetType(s)> has gone through several forms in the search for an optimum solution for classifying targets– First, adoption of Hands-On Universe image database list

using normal strings like “globular cluster” and “galaxy”– Extension of HOU list– Adoption of UCD-like form (e.g. “stars.supernova”,

“galaxies.spiral”)– Currently (temporarily) an Eclipse+Java-friendly GUI-like

form “stars_:_supernova” (Don’t ask - a long, long, story.....)

• Example:– <Target name=“SN2005J”>

<Classification>stars_:_supernova</Classification><Classification>galaxies_:_spiral</Classification>...

</Target>

VOConcepts @ VOEvent 2005-12-05T13:30:00+8, Tucson

VOConcepts• Attempt to produce a UCD-like target

classification scheme for RTML, HTN & VOEvent and perhaps IVOA

• Use of UCD-like syntax (compatibility)• Based upon ApJ/A&A/MNRAS keyword lists• Extensive enough to be useful• (Barely) Short enough to be initially acceptable• “Published” April 2005 @

monet.uni-goettingen.de/twiki/bin/view/VOEvent

• Submitted to IVOA UCD core discussion forum, but very limited response or even interest at first

• More recent email discussions with Andrea Preite-Martinez (her versions 0.1 and 0.2) resulted in her proposed “IVOA Standard Vocabulary”

• Version 0.3 of Andrea’s IVOA proposal distributed

VOConcepts @ VOEvent 2005-12-05T13:30:00+8, Tucson

Syntactical Basis of VOConcepts

• Use of normal vocabulary, minimal abbreviations, standard hyphenation and capitalization (“Herbig-Haro”, “supernovaRemnant”)

• Primary list of (mostly plural) general groupings– process (physical processes, events, features), Sun,

solarSystem, stars, ISM, Galaxy, galaxies, cosmology • List of (mostly singular) sub-groupings (e.g.

stars.cluster)• Concatenation with semi-colons (just like UCDs)

– e.g. process.burst;em.gamma = em.gamma;process.burst = “GRB”

– Enables cross-referencing of concepts, but shouldn’t be overdone!

• Object classes with architypes use appended “-class” to avoid identification with individual named objects– e.g. stars.variable.deltaCep-class = “Cepheids”

• Set of “atoms” for real-world purposes– e.g. obj.calib.* (UCD uses obj), obs.calib.*, weather.*,

...

VOConcepts @ VOEvent 2005-12-05T13:30:00+8, Tucson

VOConcepts Examples• Gamma-Ray Burst = process.burst;em.gamma• Classical Dwarf Nova =

stars.variable.cataclysmic.dwarfNova.UGem• Type Ia Supernova = stars.supernova.typeIa• “Orphan” Optical Transient = process.burst;em.opt• RR Lyrae star =

process.pulsation;stars.variable.RRLyr-class• Exoplanet transit = process.eclipse;stars;planets• Pulsar glitch = process.glitch;em.radio;stars.neutron• Starburst galaxy = galaxies.starBurst• Closely interacting galaxies =

galaxies;process.merging• Guide star = obj.calib.guide• Flatfield observation = obs.calib.flatfield• Lunar occultation =

process.occultation;stars;planets.satellite

VOConcepts @ VOEvent 2005-12-05T13:30:00+8, Tucson

VOConcepts “IVOA Standard Vocabulary” ?

Version 0.3 makes IMHO some good and some bad modifications, e.g.

• Gravitation previously absent from UCD1 – process.gravitation.wave, *.lensing & *.microlensing

• Cumbersome “class.*” group, inconsistently applied – stars.variable.deltaCep-class (VOConcepts)

stars.variable;class.deltaCep (IVOA/SV)– stars.Be stars;class.Be but not stars.AGB

stars;class.AGB – stars.supernova.typeIa stars.superNova;class.Ia

• Redundant/inconsistent notation – ISM.cloud vs. ISM.nebula vs. ISM.region (difference?)– ISM.nebula.planetary ISM.planetaryNebula (do we want to

preserve hierarchies?)• Strange atoms like source.VeryRed, source.ExtremelyRed • Still missing important things like

– phys.particle.*– obj.calib.* to classify calibration objects (photometric, guide-

stars,...)– obs.calib.* to classify calibration observations

VOConcepts @ VOEvent 2005-12-05T13:30:00+8, Tucson

The Problems with Speaking IVOA/UCDish

• Precise but not very succinct– e.g. “QSO jet” = galaxies.active.AGN.quasar;em.radio;process.mass-

loss.jet– Probably no problem if standardized - this is all mostly for

computers• How to handle special objects? E.g.

– source.Sun;process.protuberance or Sun.protuberance?– Source.Earth;planetarySystems.satellite or Earth.Moon?– ISM.nebula.galactic or Galaxy;ISM.nebula?

• Do we need a separate vocabulary list /dictionary for human-readable / succinct concepts?– If so, who maintains which ones for whom? Longevity for long-term

querying?– VOEvent could maintain its own list, if really needed.

• Can express only global concatenation of concepts– e.g. in source;em.red;stat.extreme is the source or the redness

extreme?• What about formal ontologies (e.g. XML-based “OWL”)

– Will they eventually replace a UCD-like solution or run parallel? Should we care?

• Will the IVOA adopt an acceptable initial “Standard Vocabulary” fast enough for VOEvent and RTML to adopt it or do we have to keep pushing ahead on our own?

VOConcepts @ VOEvent 2005-12-05T13:30:00+8, Tucson

My Suggestion• Submit LOTS of constructive suggestions/corrections for

IVOA/SV pre-proposal to Andrea from broad potential user-base: she is our best guide/path through the IVOA jungle

• Insist upon consistency, reasonableness, and real-life usefulness

• Insist upon a system which can be extended using a clear set of rules (e.g. IMHO dump class.* atoms since they can’t be applied consistently; avoid unnecessarily parallel hierarchies)

• Insist upon a deadline for the adoption of an initial “Standard Vocabulary” with the 100 most needed concepts which can immediately be adopted by VOEvent, RTML, and HTN, thus creating facts for the rest of the IVOA community– e.g. compile a list and simply vote!

• Worry about general acceptance / IAU later : everyone will simply have to follow!

VOConcepts @ VOEvent 2005-12-05T13:30:00+8, Tucson

(RTML slide)

VOConcepts @ VOEvent 2005-12-05T13:30:00+8, Tucson

Remote Telescope Markup Language

• Original goal : describe simple observing imaging proposal using XML (DTD Version 2.1)

• Now (Schema Version 3.1) : – describes complex imaging/spectroscopic observing

proposals– can serve as the medium for reserving remote observing

time-blocks– represents complex scheduling constraints– represents “Phase I & II” information– documents available telescope/observatory resources– documents most important details of a completed

observation– can be used as input/output of generalized exposure

simulators– can serve as the medium for arbitration of services

(HTN)