The table contains optical and X-ray data of all 1252 detected Gliese stars. Note that many entries are actually binaries. In a few cases, both components have been detected separately. However, in most cases, the detected X-ray source is attributed to both components and no attempt is made to split up the X-ray flux. As a consequence, care must be taken when interpretating the catalogue information for binaries. For example, in the case of Gl 244 A, B (= Sirius), the X-ray flux is known to arise exclusively from the hot white dwarf B-component, while in the case of Gl 280 A, B (= Procyon) the X-ray emission comes from the late-type primary component. In our catalogue, however, the same X-ray flux is attributed to the A- as well as the B-components.
Also note that the quoted count rates are mean count rates during the survey observations, computed as the ratio of total number of counts and integrated exposure time. In some cases, these numbers can strongly be affected by individual flare events (e.g., Gl 877 = EV Lac, see Schmitt 1994; see also Haisch & Schmitt 1994).
The columns of the table contain the following information:
Column 1: Designation of catalogue entry. Where available, we prefer the original Gliese (Gl), Gliese-Jahreiß (GJ), or Woolley (Wo) designation. Stars without such a number are named according to one of the following other catalogues (in hierarchical order): Henry Draper (HD), Giclas (G), Luyten Half Second (LHS), Durchmusterung (BD or CD), or various other designations (LTT, LP, GR, Steph, Rob, BPM, AC). Only in very few cases, where we did not find any common designation, do we use the approximate celestial position instead. Stars marked with an asterisk were detected in the "survey repair'' observations (cf. Sect. 2.1).
Column 2: V magnitude (from Gliese catalogue).
Column 3: B-V color index (from Gliese catalogue).
Column 4: MK spectral classification (from Gliese catalogue).
Column 5: Distance to the star as given by the Hipparcos parallaxes.
Column 6: effective exposure time in seconds.
Column 7: mean PSPC count rate in counts per second.
Column 8: error of PSPC count rate.
Column 9: likelihood of existence (cf. Sect. 2.1); a value of 999 indicates a source existence likelihood of 999 or greater.
Column 10: offset in arcsec between optical and X-ray position.
Column 11: hardness ratio HR = (H-S)/(H+S) (cf. Sect. 2.3).
Column 12: error of hardness ratio.
Column 13: apparent X-ray flux (0.1-2.4 keV) in 10-14 ergcm-2 s-1 (see Sect. 2.3).
Column 14: X-ray luminosity derived from the distance as given in Col. 5. The values are given in units of 1027ergs-1.
We especially thank H. Jahreiß for providing us with an electronic version of the Gliese catalogue and the newest parallaxes of the X-ray detected Gliese stars. The ROSAT project is supported by the Bundesministerium für Bildung, Forschung und Technologie (BMBF/DLR) and the Max-Planck-Gesellschaft (MPG). We would like to thank our collegues from the MPE ROSAT group for their support.
Copyright The European Southern Observatory (ESO)