PPM-扩展（PPMX）-位置和自行目录
PPM-Extended (PPMX) - a catalogue of positions and proper motions
摘要：
目的：我们建立了一个目录PPM扩展（PPMX）的ICRS系统，这是完整的到一个定义明确的极限幅度，并包含目前最好的自行适合在银河系中的运动学研究。研究方法：我们执行严格的加权最小二乘调整的个人观察，分布在一个多世纪，以确定平均位置和自行。PPMX的恒星内容来自GSC 1.2，并在明亮端补充了ARIHIP，PPM和Tycho-2等目录。所有观察结果都根据其各自的准确性进行了加权。对目录进行了筛选，以排除各种来源目录中的虚假条目。PPM-Extended（PPMX）是一个包含18，088，920颗恒星的星表，包含天体测量和光度信息。在GSC测光系统中，它的极限星等约为15.2等。PPMX由三部分组成：a）在UCAC 2星等系统中完成的直到R_U = 12.8的巡天; b）具有高精度自行的额外恒星; c）在2 MASS中识别的GSC 1.2中的所有其他恒星。对于66%的巡天星（a）和高精度恒星（b），自行的典型精度为2 mas/y，而所有其他恒星的自行精度约为10 mas/y。PPMX包含来自ASCC-2.5和2 MASS的光度信息。
英文摘要：
Aims: We build a catalogue PPM-Extended (PPMX) on the ICRS system which is complete down to a well-defined limiting magnitude and contains the best presently available proper motions to be suited for kinematical studies in the Galaxy. Methods: We perform a rigorous weighted least-squares adjustment of individual observations, spread over more than a century, to determine mean positions and proper motions. The stellar content of PPMX is taken from GSC 1.2 supplemented by catalogues like ARIHIP, PPM and Tycho-2 at the bright end. All observations have been weighted according to their individual accuracy. The catalogue has been screened towards rejecting false entries in the various source catalogues. Results: PPM-Extended (PPMX) is a catalogue of 18,088,920 stars containing astrometric and photometric information. Its limiting magnitude is about 15.2 in the GSC photometric system. PPMX consists of three parts: a) a survey complete down to R_U = 12.8 in the magnitude system of UCAC2; b) additional stars of high-precision proper motions, and c) all other stars from GSC 1.2 identified in 2MASS. The typical accuracy of the proper motions is 2mas/y for 66 percent of the survey stars (a) and the high-precision stars (b), and about 10 mas/y for all other stars. PPMX contains photometric information from ASCC-2.5 and 2MASS.
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