PPM-Extended (PPMX) - a catalogue of positions and proper motions

TL;DR

The PPM-Extended (PPMX) catalogue provides a comprehensive, accurate, and well-structured dataset of over 18 million stars with positions and proper motions, suitable for galactic kinematic studies.

Contribution

We constructed the PPMX catalogue by integrating multiple data sources and applying rigorous weighted least-squares adjustments to produce the most accurate proper motions available.

Findings

Catalogue contains over 18 million stars with positions and proper motions.

Typical proper motion accuracy is 2 mas/y for most stars.

Catalogue is complete down to magnitude 15.2 in the GSC system.

Abstract

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.