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Data Modeling Meeting

ESO, Garching, Jan. 23/24, 2003

Initials Participant
PB Pascal Ballester
FB Francois Bonnarel
PD Pierre Didelon
MD Markus Dolensky, chair
JH Jonas Haase
ML Marco Leoni
MIL Mireille Louys
JMD Jonathan McDowell
AM Alberto Micol, minutes
BP Benoit Pirenne
BV Bruno Voisin


Day 1, Room 231, 1:30 pm - open ended (~5 pm)

# Time Moderator Topic
1 13:30 MD Intro, report on IVOA working groups
2 9:45 PF status of Aladin
3 11:00   coffee break

M Dolensky: report on IVOA meeting conclusions J McDowell: status of data modeling efforts M Louys: start an open discussion of - reduction pipelines - data quality - hierarchy/granularity in the metadata - versioning


Day 2: room 232, 9am - max 12pm

- F. Bonnarel: how data model + VOTable was used in AVO GOODS first light demo

AOB (P.Didelon ?)

-M.Dolensky: events 2003, plans wrap up

Notes About Individual Agenda Items

MD: IVOA meeting conclusions

JMD: VO Data Models: status

boston meeting goals were: compare existing models ... ... compliant data model: first: to write the concept one wants to describe second: UML or equivalent based model third: convert UML to XMI or equiv. and verify model schema satisfies VO DM standards (see below) fourth(optional): provide a reference XSD schema and XML instance examples. IVOA InterOp. group can adopt model as a recommended VO model for the given concept.

Conforming IVOA Data Models unique URI unique name version description curation metadata url for white paper class descriptions: - name and description - attributes, name,type,quantity,cardinality,defaults, units? - properties - methods

bandpass methods and attributes effective lambda min and max lambda/freq/energy/wave numbers transmission curve (add or multiply?) theoretical transmission curves (also as function of time, temperature)

uncertainties on each number! quality object (non numerical description)

problems: red leaks, periodic filters, wedge and band stop (notch) filters multiple filters atmospheric transmission ?

bandpass attributes - name, generic name, waveband name - central and end wavelengths - measured ot theoretical transmission function what about zeropoints ?

bandpass classes NOT DISCUSSED

Wavelength/Frequency model Wavelength 512.02 nm



(#PC: 512.02?)

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 better than inheritance (HAS-A instead of IS-A)

what is data, hypermaps, images, tables, documents, code, plots, links, etc)

ML: open discussion - reduction pipelines - data quality - hierarchy/granularity in metadata - versioning

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

Granularity: BV? better having XSLTs onto your XML DM ?

Day 2

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

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.

AM: HST pipeline ...

MD: IVOA Data Modeling Standardisation WG


Lead: Jonathan McDowell (CfA) Members: Alberto Micol (ST-ECF), Mireille Louys (CDS), ?Dave Giarretta (ASTROGRID)?, ? someone else ?

Remarks (scope, goal, ...)

for events 2003 see Avo:AvoEvents

us-vo Nashville, June aas meeting (but sidney ...) NVO team meeting, ?, March, status reports

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.

(created by MarkusDolensky 08.02.2023@14:38:07)

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