A&A 405, 1169-1176 (2003)
DOI: 10.1051/0004-6361:20030564
Increasing the reliability of ISOCAM cross-identifications by use of a probability pattern
S. Derriere1, S. Ott2 and R. Gastaud31 Observatoire Astronomique de Strasbourg, 11 rue de l'Université, 67000 Strasbourg, France
2 ISO Data Centre, Science Operations and Data Systems Division, European Space Agency, Villafranca del Castillo, PO Box 50727, 28080 Madrid, Spain
e-mail: sott@iso.vilspa.esa.es
3 CEA/DSM/DAPNIA Saclay, Service d'Astroph., L'Orme de Merisiers, Bat. 709, 91191 Gif-sur-Yvette, France
e-mail: rgastaud@cea.fr
(Received 16 May 2002 / Accepted 13 March 2003)
Abstract
The built-in play at the wheels of the ISOCAM instrument
affects the accuracy of the astrometry of sources from the ISOCAM
Parallel Catalogue. We present the results of different methods for
cross-identifying ISOCAM sources with reference catalogues
in the optical (USNO-A2.0) and in the near infrared (2MASS).
For a sample of 7197 ISOCAM sources, the fraction having a
real counterpart in the USNO and 2MASS catalogues was estimated
to be 95% and 91% respectively.
Using a nearest neighbor method for cross-identification, only 74%
of the possible associations with USNO (79% with 2MASS) are
retrieved. With the use of a so-called probability pattern to perform the
associations, these values increase to 77% for USNO and 83% for
2MASS. In addition, the overall reliability of associations
increases from 77 to 87% with USNO, and from 81 to 90% with 2MASS.
Key words: catalogs -- astrometry -- methods: data analysis -- methods: statistical -- infrared: general
Offprint request: S. Derriere, derriere@astro.u-strasbg.fr
© ESO 2003