2 Description of the table

Table 1 lists the 130 HMXBs. The format of the table is similar to that of the previous one (van Paradijs 1995) and the well-known work of Bradt & McClintock (1983), of which the present catalogue is meant to be an update. In the table the sources are ordered according to right ascension; part of the (mainly numerical) information on a source is arranged in seven columns, below which for each source additional information is provided in the form of key words with reference numbers [in square brackets]. The columns have been arranged as follows.

In Col. 1 the first line contains the source name, with rough information on its sky location according to the convention hhmm $\pm$ ddd. Here hh and mm indicate the hours and minutes of right ascension, ddd the declination in units of 0.1 degree (in a small number of cases, the coordinates shown in the name are given with more, or fewer, digits). However, for a ROSAT source the name is always given in the form of hhmm.m $\pm$ ddmm. The prefix J indicates a name based on J2000 coordinates. Otherwise, 1950 coordinates were used in the name. Alternative source names are given in the second line. The third line of Col. 1 lists survey catalogues and experiments in which the source was listed and detected, respectively. The following abbreviations have been used.

$\bullet$ A: Ariel V sky survey;
$\bullet$ AS: ASCA;
$\bullet$ B: BeppoSAX;
$\bullet$ C: Compton $\gamma$-ray Observatory;
$\bullet$ E: Einstein Observatory;
$\bullet$ Exo: Exosat;
$\bullet$ G: Ginga;
$\bullet$ Gr: Granat;
$\bullet$ H: HEAO A-1 sky survey;
$\bullet$ Ha: Hakucho;
$\bullet$ K: Kvant;
$\bullet$ M: MIT OSO-7 sky survey;
$\bullet$ OAO: Orbiting Astronomical Observatory;
$\bullet$ R: ROSAT;
$\bullet$ S: SAS 3;
$\bullet$ SL: Space Lab;
$\bullet$ T: Tenma;
$\bullet$ U: Uhuru sky survey;
$\bullet$ V: Vela-5 and -6 satellites;
$\bullet$ X: Rossi XTE.

In the first line of Col. 2, the source types are indicated with a letter code, as follows:

$\bullet$ P: X-ray pulsar;
$\bullet$ T: transient X-ray source;
$\bullet$ U: ultra-soft X-ray spectrum. These sources include black-hole candidates; some "extreme ultra-soft'' (EUS) source may be white dwarf (WD) on whose surface steady nuclear burning takes place.

In the third line of Col. 2, we provide some information on the type of observation from which the source position has been derived. The following abbreviations have been used: o, optical; x, X-ray; r, radio; IR, infrared. A reference on the source position is given below the columnar information under "pos.''. In addition, we give an indication of the accuracy of this position, in the form of equivalent (90 percent confidence level) error radii, but in several cases this can only be considered an approximation (e.g. when the error box is not circular). When no accuracy is quoted, it is about one arcsecond or better.

Column 3 contains in the first two lines the right ascension (RA) and declination (DEC) of the source for epoch 1950 for usual name, and for epoch 2000 for the sources with the names of J2000 coordinates. RA is given as hhmmss.s to an accurcy of 0.1 s, DEC is given in $^\circ\,\hbox{$^\prime$ }\,\hbox{$^{\prime\prime}$ }$, to an accuracy of $1\hbox{$^{\prime\prime}$ }$. The third line gives the galactic longitude and latitude to an accuracy of 0.1$^\circ$(except for sources close to the galactic center, where these coordinates are given to 0.01$^\circ$).

The first and second lines of Col. 4 give names of an optical counterpart. The third line contains a reference to a finding chart. An asterisk followed by a number or letter refers to star numbers used in the finding chart; "star" refers a star in the finding chart that has not been assigned a number or letter. Many optical counterparts have been indicated with a variable-star name, as given in the General Catalogue of Variable Stars and in recent name lists of variable stars as published regularly in the IAU Information Bulletin on Variable Stars, or a number in a well-known catalogue (e.g., HD, SAO). For X-ray sources in globular clusters, the cluster name is here given, in addition to the name of a stellar optical counterpart.

The fifth column contains some photometric information on the optical counterpart. In the first line, the apparent visual magnitude, V, and the color indices B-V, and U-B, are listed. The second line contains the spectral type of the optical counterpart and an estimate of the interstellar reddening, E_B-V.

In Col. 6, the average X-ray flux, or the range of observed X-ray fluxes (2-10 keV, unless otherwise indicated), is given, in units of

$$\begin{eqnarray*}1~\mu{\rm Jy} & = &10^{-29}~{\rm erg~cm}^{-2}~{\rm s}^{-1}~{\rm... ... & 2.4 \ 10^{-12}~{\rm erg~cm}^{-2}~{\rm s}^{-1}~{\rm keV}^{-1}. \end{eqnarray*}$$

The first line in Col. 7 gives the orbital period in days. The second line contains for X-ray pulsars the pulse period, in seconds.