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The VOPSAT image database


NGC4945,Seyfert2 barred spiral galaxy. Its active nucleus hosts
a rapidly rotating black hole.
ESO Schmidt image digitized by MAMA.

During the eighties and nineties, several thousands original photographic plates had been digitized with the MAMA microdensitometer and calibrated to meet the specific objectives of a number of national and international projects in a variety of scientific domains: clusters of galaxies, samples of quasar candidates, young stellar objects, variable stars, stellar populations in the solar neighbourhood, tidal effects on open and globular clusters, microlensing...

More recently, our team has undertaken digitizing and making available to the astronomical community three atlases: ESO-R and southern part of POSSI-E in the R band, SRC-J in the B band.

The resolution (0.6 arcsec) of the digitized images provided by the MAMA microdensitometer, together with the astrometric accuracy of the UCAC catalog and specific software developments, offer new possibilities for multi-wavelength cross-identifications, multi-epoch studies, or preparation of new observations.

The VOPSAT (VO Paris SOuthern Atlas) image data base

VOPSAT is accessible through the Virtual Observatory SIAP ("Simple Image Access Protocol") service: and

The base hosts the 606 ESO-R, 894 SRC-J, and 352 southern Palomar1-E fields

The project is conducted in partnership with the VO Paris Data Centre and the ALADIN group (CDS). It takes advantage of software developments due to the TERAPIX team at IAP (Institut d’Astrophysique de Paris), in particular for image resampling and reprojection.


  • The first version of the mosaicing software already provides images up to several tens of square degrees covering neighbouring Schmidt plates, with elimination of spurious regions such as calibration steps and preservation of the astrometric quality. (The front page of the last ADASS proceedings shows an exemple of the VOPSAT mosaicing).
  • This astrometric quality can be controlled with the "ASTROCHECK" tool.
  • The catalogs extracted from the images will be available to users with overlay possibilities, providing positions and magnitudes of the detected objects.