spm4

SPM Catalog 4

spm4 aitoff projection

The Yale/San Juan Southern Proper Motion Catalog 4


The SPM4 is the most extensive SPM catalog version to date and in many ways is the culmination of the 47-year Southern Proper Motion program.  Absolute proper motions, positions, and B,V photometry are given for over 100 million stars and galaxies, down to a magnitude of V=17.5.  Sky coverage is from declination -20 degrees to the south celestial pole.  Cross references to the 2MASS near-infrared catalog are also included, as is the 2MASS JHK photometry.

The catalog is based on a combination of photographic and CCD observations, all made with the 51-cm double astrograph of Cesco Observatory in El Leoncito, Argentina.  The photographic plates were scanned using the Precision Measuring Machine at the US Naval Observatory's Flagstaff Station. The raw pixel data were saved and later analyzed at the US Naval Observatory in Washington to obtain image centers and photometric indices for all detectable images.  CCD observations comprise the second-epoch astrometry for roughly two thirds of the area covered.  The absolute proper motions are tied to the ICRS at the bright end, via Hipparcos stars, and to external galaxies at the faint end.  The final precision of the SPM positions and absolute proper motions is approximately 30 to 150 mas and 2 to 10 mas/yr, respectively.  Systematic errors in the proper motions are still being evaluated but are estimated to be on the order of 1 mas/yr.


The SPM4 Catalog is available for ftp download as a set of bzip2 and plain ascii files, including an explanatory readme file and simple Fortran code for extracting subsets of the data.  The total size of these files is approximately 4.3 gigabytes.  Alternatively, a DVD-R copy of the catalog may be obtained upon request to Terry Girard at the address below.

To obtain the SPM4 Catalog via ftp, click here.

For a DVD copy of the SPM4 Catalog, send a request to

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This page last modified by T. Girard - January 5, 2010.