Astron. Astrophys. Suppl. Ser. 143, 391-403

ROSAT HRI catalogue of X-ray sources in the LMC region

M. Sasaki - F. Haberl - W. Pietsch

Send offprint request: M. Sasaki,
e-mail: manami@mpe.mpg.de

Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, D-85748 Garching, Germany

Received December 30, 1999; accepted January 20, 2000

Abstract:

All 543 pointed observations of the ROSAT High Resolution Imager (HRI) with exposure times higher than 50 s and performed between 1990 and 1998 in a field of 10$^\circ$ $\times$10$^\circ$ covering the Large Magellanic Cloud (LMC) were analyzed. A catalogue was produced containing 397 X-ray sources with their properties measured by the HRI. The list was cross-correlated with the ROSAT Position Sensitive Propotional Counter (PSPC) source catalogue presented by Haberl & Pietsch (1999) in order to obtain the hardness ratios for the X-ray sources detected by both instruments. 138 HRI sources are contained in the PSPC catalogue, 259 sources are new detections. The spatial resolution of the HRI was higher than that of the PSPC and the source position could be determined with errors mostly smaller than 15 $^{\prime\prime}$ which are dominated by systematic attitude errors. After cross-correlating the source catalogue with the SIMBAD data base and the TYCHO catalogue 94 HRI sources were identified with known objects based on their positional coincidence and X-ray properties. Whenever more accurate coordinates were given in catalogues or literature for identified sources, the X-ray coordinates were corrected and the systematic error of the X-ray position was reduced. For other sources observed simultaneously with an identified source the coordinates were improved as well. In total the X-ray position of 254 sources could be newly determined. The catalogue contains 39 foreground stars, 24 supernova remnants (SNRs), five supersoft sources (SSSs), nine X-ray binaries (XBs), and nine AGN well known from literature. Another eight sources were identified with known candidates for these source classes. Additional 21 HRI sources are suggested in the present work as candidates for SNR, X-ray binary in the LMC, or background AGN because of their extent, hardness ratios, X-ray to optical flux ratio, or flux variability.

Key words: catalogues -- galaxies: Magellanic Clouds -- galaxies: stellar content -- X-rays: galaxies -- X-rays: stars