Next: SDFITS: A Standard for Storage and Interchange of Single Dish Data
Up: Distributed Data Systems, Data Mining
Previous: On-line Access to Very Large Catalogues
Table of Contents -
Subject Index -
Author Index -
PS reprint -
Bonnarel, F., Genova, F., Bienayme, O., Dubois, P., Egret, D., Fernique, P., Jasniewicz, G., Lesteven, S., Ochsenbein, F., Ortiz, P., & Wenger, M. 2000, in ASP Conf. Ser., Vol. 216, Astronomical Data
Analysis Software and Systems IX, eds. N. Manset, C. Veillet, D. Crabtree (San Francisco: ASP), 239
The Role of the CDS Information Hub in the Cross-identification of
Large Surveys
F. Bonnarel, F. Genova, O. Bienayme, P. Dubois, D. Egret,
P. Fernique, G. Jasniewicz 1, S. Lesteven,
F. Ochsenbein, P. Ortiz, M. Wenger
CDS Observatoire Astronomique de Strasbourg, 11 rue de l'Université,
F67000 Strasbourg France
Abstract:
The services developed by the Centre de Données astronomiques de
Strasbourg (CDS) will play a major role in the cross-identification of
objects from large surveys. SIMBAD provides the identification of
objects published in the literature, or from reference catalogues; the
VizieR catalogue browser can be used to browse through the survey result
catalogues, and to compare them to other catalogues and published
tables, and the ALADIN sky atlas allows one to overlay survey catalogues
on images of the sky, together with SIMBAD, NED, and catalogues and
published tables from VizieR.
Several aspects of the recent CDS development pave the way to this usage
of the CDS services: the inclusion of TYCHO in SIMBAD, the
implementation of the public DENIS and 2MASS catalogues in VizieR, and
the release of the ALADIN Java interactive tool. The ESO/CDS data mining
project, and the AstroGLU discovery tool, aim at providing advanced
tools for cross-identification and access to distributed, heterogeneous
information. The development of generic tools, such as the CDS GLU
system (Générateur de Liens Uniformes), and the definition of
standards for information exchange, in cooperation in particular with
the archive providers and the journals, and in the frame of project such
as ISAIA or DYNACORE, are also keys to provide 'clever' and
'transparent' links between all the information needed for the
scientific interpretation of observations.
Suppose that we have sources from a very large catalog (for example the
DENIS infrared survey). VizieR allows very fast access by coordinates to
this catalog either directly from its http interface or from the Aladin
Interactive Sky Atlas. This is also the case for the USNO, GSC and 2MASS
catalogs (Derrière et al. 2000, and references therein). Aladin
(Fernique et al. 2000 and references therein) is an access tool to
reference images of the sky - digitized Schmidt surveys from DSS1,
MAMA/CAI and recently also from DSS2 - and to various CDS (and others)
databases and archives. Figure 1 show a DSS1 image of the 30 Doradus
region in the LMC.
Figure 1:
DSS1 image of the 30 Doradus Nebula within Aladin.
 |
In a second step (Figure 2) X-ray sources (WGACAT catalog) from VizieR
and SIMBAD objects have been overlayed on the image in addition to DENIS
sources, as tentative cross-identifications for them. From the overlays
we can produce a small clickable list, and from there go to the content
of VizieR and SIMBAD for these objects.
SIMBAD provides coordinates, magnitudes, spectral type, bibliographical
references with links to the ADS services. Links to IUE spectra and
HEASARC measurements
are also available. VizieR provides data from more than 2600 astronomical
catalogs, tables of journals, and observatory archives logs with links to the
archives (IUE, HST for example).
In our example, a DENIS source has been associated visually by position
to two Simbad objects: an O star ([P93] 1619) and an infrared source
(Dor IRS 143). In addition an Xray source is very close (marked area on
the image in Figure 2). It is likely that the DENIS source and the two
SIMBAD objects are the same star. But the Xray source had been
previously cross-identified with a other F star (HD 269929, seen from
the WGACAT record) with an inaccurate position.
The assessment of the proper cross-identification really requires a
study of all the available information about the objects.
This example illustrates how the CDS on line services can help to build
cross-identification strategies on individual cases, or give
information to solve problems occurring in cross-identification
processes.
Of course, cross-identification of long lists of objects or of whole
catalogs requires to process large quantities of data and cannot be done
interactively. CDS also provides client routines for automatic access to
Simbad, catalogs in Vizier, and images from the Aladin server.
Figure 2:
Overlays and database content.
 |
Astroglu, provides a list of URL of databases containing information on
astronomical objects. It is based on a dictionary of remote services
maintained in the framework of the GLU system. A customization of this
service for helping observers on optical telescopes (DYNAGLU) is being
developed in the frame of the EC project DYNACORE.
In order to find its way among the catalog jungle
for positional cross-correlation, it is useful to select among the
catalogs for example by Column Content or Wavelength coverage. This is
the aim of the ESO/CDS data mining tool, which is an ESO/CDS
collaboration (Ortiz et al. 1999).
An XML formatting of tabular data is being discussed in collaboration
with other partners (Ochsenbein et al. 2000). XML output of VizieR has
been implemented to facilitate data exchange.
The next step in providing cross-identification tools will be to
provide links between SIMBAD and VizieR. This will allow the users to
retrieve all the measurements in various catalogs for objects in the
SIMBAD database. These links will be based on the availability of
cross-identifications in SIMBAD, in the catalogs, and on position.
A database for very large catalogs is currently being studied at
CDS. The goal is to manage several survey catalogs in the same
commercial object oriented database (Objectivity), and to provide fast
access for sampling by the main parameters, using multicriteria
indexation.
All these services and related documentation are accessible at the
address:
http://cdsweb.u-strasbg.fr. More about recent developments
of the CDS services can be found in the paper by Genova et al. (2000) in
these proceedings.
References
Derrière, S., Ochsenbein, F., & Egret, D. 2000, this volume,
235
Fernique, P. & Bonnarel, F. 2000, this volume, 71
Genova, F., Bonnarel, F., Dubois, P., Egret, D., Fernique,
P., Jasniewicz, G., Lesteven, S., F.Ochsenbein, F., & Wenger, M. 2000,
this volume, 693
Ochsenbein, F., Albrecht, M., Brighton, A., Fernique, P.,
Guillaume, D., Hanish, R., Shayai, E., & Wicenec, A. 2000, this volume,
83
Ortiz, P. F., Ochsenbein, F., Wicenec, A., & Albrecht, M. 1999, in ASP Conf. Ser., Vol. 172, Astronomical Data Analysis software
and Systems VIII, ed. David M. Mehringer, Raymond L. Plnate, & Douglas
A. Roberts (San Franciso: ASP), 379
Footnotes
- ... Jasniewicz1
- GRAAL, Université Montpellier 1, F34000 Montpellier France
© Copyright 2000 Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, California 94112, USA
Next: SDFITS: A Standard for Storage and Interchange of Single Dish Data
Up: Distributed Data Systems, Data Mining
Previous: On-line Access to Very Large Catalogues
Table of Contents -
Subject Index -
Author Index -
PS reprint -
adass@cfht.hawaii.edu