An investigation of the absolute proper motions of the XPM catalogue




XPM-1.0 is the regular version of the XPM catalogue. In comparison with XPM, this astrometric catalogue of about 280 millions stars covering the entire sky from −90° to +90° in declination and in the magnitude range 10 < B < 22 mag is somewhat improved. The general procedural steps were followed as for XPM, but some of these were performed on a more sophisticated level. The XPM-1.0 catalogue contains the star positions, the proper motions and the Two-Micron All-Sky Survey (2MASS) and United States Naval Observatory (USNO) photometry of about 280 million sources. We present some investigations of the absolute proper motions of the XPM-1.0 catalogue and also important information for users of the catalogue. Unlike the previous version, XPM-1.0 contains proper motions over the whole sky without gaps. In fields covering the zone of avoidance or those that contain fewer than 25 galaxies, quasi-absolute calibration was performed. The proper motion errors vary from 3 to 10 mas yr−1, depending on a specific field. The zero-point of the absolute proper motion frame (the absolute calibration) was specified with more than one million galaxies from 2MASS and USNO-A2.0. The mean formal error of absolute calibration is less than 1 mas yr−1.