Data Modeling Meeting

ESO, Garching, Jan. 23/24, 2003

Initials Participant Affiliation
PB Pascal Ballester ESO
FB François Bonnarel CDS
PD Pierre Didelon Terapix
MD Markus Dolensky, chair ESO
JH Jonas Haase ST-ECF
ML Marco Leoni ESO
MIL Mireille Louys CDS
JMD Jonathan McDowell CfA
AM Alberto Micol, minutes ESA
BP Benoît Pirenne ESO
BV Bruno Voisin Astrovirtel visitor


Day 1, Room 231, 1:30 pm - 5:15 pm

# Time Moderator Topic
1 13:30 MD Intro, report on IVOA working groups
2 14:00 JMD IVOA data models
  15:00   break
3 15:20 MIL start open discussion of ...
      - reduction pipelines
      - data quality
      - hierarchy/granularity
      - versioning

Day 2, Room 232, 9 am - 12 am

# Time Moderator Topic
4 9:00 FB Aladin GOODS tree and IDHA data model
5 9:50 JMD Chandra pipeline architecture
6 10:30 AM HST pipeline architecture
  11:10   break
7 11:25 MD Formation of IVOA Data Modeling Standardization Group
    MD Events 2003

Meeting split for informal discussions within ESO.

Notes About Individual Agenda Items

1 [MD]: IVOA meeting conclusions

2 [JMD]: VO Data Models: status

report on boston meeting, Oct 2002

See above minutes for meaning of conforming data model and modelling exercise on spectral bandpass.

Wavelength/Frequency model



  (#PC: <FRAVERGY TYPE="wavelength" UNIT="nm">512.02</WAVELENGTH>?)

What is an image?

  • sparse (with bad pixel map) is ok
  • must have regular pixellated array
  • must have pixels with scalar simple data types (int, real, complex, char?)
  • can have n dimensions, n arbitrary

Aggregation is generally better/simpler than inheritance (HAS-A instead of IS-A)

What is data, hypermaps, images, tables, documents, code, plots, links, etc?

related documents

3 [MIL]: open discussion on ...

  • reduction pipelines
  • data quality
  • hierarchy/granularity in metadata
  • versioning

IDHA (Images Distribuées Hétérogènes pour l'Astronomie) team:

  • CDS FB, A.Oberto, et al
  • LSIIT ML, C.Collet
  • IAP, PD, Y.Mellier, E.Bertin
  • QUB: F.Murtagh

images in astronomy

  • A. metadata definition for image sets in diverse arch.
  • B. multicolor image analysis for obj. recognition and cross identification

Goal: provide a mode for astronomical image data

a) reduction pipeline

  • [JMD] 'region object' to describe FOV
  • make more general object which has a common concept for raw and processed images

b) data quality

  • measure for quality: dm richness (detailed), traceability (raw<=>publi.)

c) granularity

  • [BV] How about applicability XSLTs to manipulate XML DMs?
  • raw - cal. - mosaic - rgb ...

d) versioning

  • feedback loop: obs. - reduc. - visual. - interpret. (and back to obs.)
  • software versioning/data versioning

Day 2

4 [FB]: How data model + votable was used in AVO GOODS demo

Bonnarel, Louys, Boch, Fernique, Schaaf, Derriere, Ochsenbein

from datamodel to xml

  • visions of data model must be translated in documents for describing metadata (different scenarii for different users/applications)
  • xml good for exchanging
  • votable or some other dtd ? -> votable because already accepted
  • how to code a Tree (partial view of a DM) into a table oriented DTD?
  • chance: definition of VOTable RESOURCE is recursive (1->n links)
  • each class of the model is defined as a RESOURCE (fixed name, no ID in order to allow multi-occurance), with a specific table part
  • children classes as nested resources
  • [JMD]: How to link a filter in the Observing_group table to the filter given in the filter resource?
  • GOODS image server has more functionalities than public aladin; public aladin will inherit those, but not before summer
  • SIAP is flat, no hierarchy, output = single table

5 [JMD]: Chandra pipeline

chandra -> telemetry -> fits files with mnemonics (Level 0)

Level 1: takes level 0 data -> calibrated scientific file

Events ASOL (Aspecs solution, geometry vs time ra,dec,roll(t)), spacecraft attitude, bending of telescope tube, (1 arcsec within an observation!) HK, temperature, radiation environment, etc -> ra, dec for all photons,

between level 1 and 2: observation can be split up -> level two combines them

typical exptime: 50ksec to 100ksec (some 1ksec, some 1Msec)

level 2 removes garbage: L2 data is just a starting point used by naive users, experts will go back to L1

L1->L2 pipeline is publicly available

L3 pipeline (not yet in place): to generate uniform source catalogs, etc

L2 event list (EVT) -> binned on the fly to provide an image of requested resolution/size

dmcopy evt2.fits[energy=2000,5500][time=from,to][bin x=3000:4000:4,y=...] produces the requested image.

IDHA covers some part of Chandra calibration system, but not the bookkeeping.

6 [AM]: HST pipeline

in contrast to Chandra ...

  • pixel info and header info come from different sources (files + DBs) when assembling raw files
  • science and engineering streams are separated for HST, but not for Chandra

[PB] reports that IAU interferometry WG exists to define data format for interferometry

7 [MD]: Forming IVOA Data Modeling Standardisation WG

  • Forum:
  • Lead: Jonathan McDowell (CfA)
  • Members
    • Alberto Micol,
    • Mireille Louys,
    • ?Dave Giarretta?,
    • others...

For events 2003 see Avo:AvoEvents

further ...

  • NVO meeting in Nashville with AAS in June
  • NVO team meeting, where?, March,

Meeting adjourned. Splinter discussions followed on:

  • a possible model for a distributed Aladin, to access both data and metadata directly from the VO data centres, without the need of storing them in the Aladin server.
  • UCD discussion
  • a possible design for a Data Model suitable for an ASTROVIRTEL Exposure-Time-Calculator-based archive search engine. Version 0.2 will be drafted and sent to participants.

Action Items

  • [JMD] announce creation of DM group to
  • [MD] register below members with Haase, Micol, Leoni, Didelon, Bonnarel, McDowell, Louys, Dolensky, Voisin

(minutes written by A. Micol; edited by M. Dolensky)

Topic attachments
I Attachment Action Size Date Who Comment
Texttxt ivoa_wg.txt manage 1.1 K 2003-01-29 - 14:00 MarkusDolensky initiating IVOA standardization working groups
Topic revision: r2 - 2003-01-29 - MarkusDolensky
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