Description of Core components for the Observation Data Model (ObsCore)

A new version of the Observation data model Core Components is currently updated and discussed on this page : ObsCoreDMvOnedotOne . It provides a better support on the axes dimensions of the data part and more compliance with Dataset/ImageDM.

Approved IVOA Recommendation: 28 October 2011

See the standard document here

Proposed Recommendation: Request For Comment period started on 3rd May 2011

Check this page ObsCoreRFC


This model is meant to gather all queriable metadata that play a role in the discovery of observation data. It is meant to be implemented using the Utypes derived from this model in a TAP/Schema implementation at various archives sites. This exercise focuses on the capability to serve 80% of the data , with reduced / reasonable implementation costs at the archive side.

Uses cases

A list of Use- cases for data queries on all possible data types has been collected by David Schade , CVO and collaborators on behalf of the IVOA Uptake committee. see the document here.


Working draft /News /Reports

We plan to deliver updates every Monday during the working group discussion period , from 01 March to 02 April 2011.

On the ObsTAPdraftDiscussion page you will find the new releases of the ObsTAP draft and a place for discussing all contentious topics to be discussed. Thanks for contributing to this discussion.

Previous drafts

First official draft version was WD-ObsCore-v1.0-20101207.pdf and can be found here. The corresponding original Tex file is attached below and currently updated following inputs during the Nara meeting.

UML Model v0.1

This is the first version of the UML diagram describing the main components for this Observation DM. The compressed archive file contains a bunch of webpages that describes the various packages and classes of the model. see the archive compressed file in 7zip here , in zip there . These are hyperlinked pages: to start with the top level , launch the index.html file and you will navigate in the various elements of the model.

ObsCoreDM v1.0/March2011 available in zip here .


From the UML classes and attributes names, one can derive Utypes strings as described in the current UTYPES draft ( Utypes WD). Utypes are built up accordingly for ObsDMCoreComponents and can be used as unique labels for each piece of information represented in the the data model. These Utype strings can be used in the TAP implementation of the model.

For most of the query mentionned in the Use-Case document here there is an item in the model covering the corresponding concept with a Utype string representing this data model element.


A set of Utypes has been identified by the Obs/TAP focus group as 'mandatory' for any service that supports an Obs/TAP discovery protocol. They are avaiblable in Table 1. Column-names will be mapped to these Utypes and used in ADQL queries. Other Utypes supported in the model and useful to identify the piece of metadata in the response of an Obs/Tap service have been listed in Table 2.


Just one list of elements for the data model with corrected Utypes, mandatory fields are shown in green. See the full table here


Feb 2011: Utype defined for the ObsCoreDM are listed in the TAP_SCHEMA.columns description in Appendix C of the ObsTap WD . See last version at

Registering ObsTAP services

Since ObsCore is just another table in an otherwise normal TAP service, the current notion is that support for ObsCore will be advertised via a flag in the TAP Capability extension. This is being discussed at TAPRegExt.

XML serialisation see the XMLObsCore page

Previous ObsTap Discussion ( 2009-2010)

Details on the model and its implementation have been discussed in various meetings and summarised in the notes attached below. Summary in the ObsTap page.

Topic attachments
I Attachment History Action Size Date Who Comment
Microsoft Excel Spreadsheetxls DataModelv1.xls r1 manage 30.0 K 2009-07-10 - 11:38 MireilleLouys keywords summary for listed UseCases - D. Schade
Microsoft Word filedoc FirstScienceUseCasesv6withUtypes.doc r1 manage 37.0 K 2009-07-10 - 12:19 MireilleLouys First Use cases with Utypes attached
Microsoft Word filedoc FirstScienceUseCasesv6withUtypes2Oct19.doc r1 manage 80.0 K 2009-11-02 - 15:57 MireilleLouys word version for first usecases
PDFpdf FirstScienceUseCasesv6withUtypes2Oct19.pdf r1 manage 418.2 K 2009-11-02 - 15:56 MireilleLouys update: Use cases / utypes constraints proposals
Compressed Zip archivezip r2 r1 manage 75.8 K 2009-07-24 - 16:04 MireilleLouys UML model for ObsDMCoreComponents
PDFpdf ObsCorelistMandatory-v1.2.pdf r2 r1 manage 103.2 K 2009-11-02 - 15:45 MireilleLouys v1.2 : update for Utypes for Mandatory fields
PDFpdf ObsCorelistMandatory-v1.3Table.pdf r1 manage 87.1 K 2009-11-09 - 09:10 MireilleLouys  
PDFpdf ObsTAP-DMlistV0_2.pdf r1 manage 224.1 K 2010-05-18 - 21:47 MireilleLouys elements and Utypes of ObsCore v0.2
Unknown file formatxlsx ObsTAP-DMlistV2_0.xlsx r1 manage 18.5 K 2010-05-18 - 21:42 MireilleLouys elements and Utypes of ObsCore v0.2
Microsoft Word filedoc TAPObsDM_ScienceUseCasesv6.doc r1 manage 79.0 K 2009-07-10 - 11:12 MireilleLouys Usecases description - D. Schade
PDFpdf WD-ObsCore-1.0-20100521.pdf r1 manage 633.1 K 2010-05-22 - 17:29 MireilleLouys New updated Version
PDFpdf WD-ObsCore-v1.0-20101207.pdf r1 manage 1366.0 K 2010-12-08 - 03:33 MireilleLouys WD presented and discussed in Nara
Compressed Zip archivezip r1 manage 931.2 K 2010-01-15 - 16:08 MireilleLouys ObsCoreComponents DM version 0.2
PDFpdf WD-ObsCoreDM-0.2-20100517.pdf r2 r1 manage 601.9 K 2010-05-19 - 05:42 MireilleLouys ObsCore draft with detailed implementation section
Compressed Zip archivezip r1 manage 99.3 K 2009-07-10 - 11:48 MireilleLouys UML diagrams for Core DM - prototype
Unknown file format7z docCoreObsUML.7z r1 manage 67.4 K 2009-07-10 - 11:49 MireilleLouys UML diagram for Core Obs Model - 7zip format
Compressed Zip archivezip r1 manage 116.7 K 2011-03-08 - 09:35 MireilleLouys Html documentation of ObscoreDM
PDFpdf optionalObstap-v1.2.pdf r1 manage 180.8 K 2009-11-02 - 15:46 MireilleLouys update : Utypes for optional fields in Obs/tap
PDFpdf optionalObstap-v1.2tab.pdf r1 manage 204.5 K 2009-11-09 - 09:46 MireilleLouys  
PDFpdf optionalObstapT2.pdf r1 manage 133.1 K 2009-10-28 - 23:01 MireilleLouys Utypes for optional fields in Obs/tap services
Compressed Zip archivezip r1 manage 2318.3 K 2010-12-09 - 13:47 MireilleLouys archive with .tex original+ images+xsl files
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Topic revision: r53 - 2015-08-17 - MireilleLouys
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