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Description
The NPM1 catalog is the first part of the Lick Northern Proper Motion (NPM) program to measure absolute proper motions, on an inertial system defined by some 50,000 faint galaxies, for some 300,000 stars over a blue apparent magnitude range from 8 to 18. There are 1246 6-degree by 6-degree fields in the NPM survey (to declination -23 degrees). The NPM1 catalog covers the 72% of the northern sky lying outside the Milky Way and contains some 149,000 stars from measures in 899 of the 1246 NPM fields. A second catalog (NPM2) will cover the NPM Milky Way fields. The Yale Southern Proper Motion (SPM) program will complete the southern sky. Each NPM field was photographed at two epochs between 1947 and 1988. The mean first and second epochs are 1950 and 1977; the average epoch difference is 27 years. The first-epoch plates were taken in the blue only; both blue and yellow plates were taken at the second epoch. Some 94000 stars were chosen anonymously for the NPM astrometric reductions and for statistical studies of stellar motions. In addition, the NPM1 catalog contains some 28000 positional reference stars, and some 27000 stars were chosen from the Lick Input Catalog of Special Stars (ICSS). The previous version of the NPM1 Catalog (I/199) deposited with the data centers (ADC and CDS) gives positions for equinox B1950 and computed epoch 1950, and is in one data file (148,940 lines) concatenating the 114 one-degree declination zones from +90 degrees to -23 degrees. Each star has an NPM1 "name" reflecting the declination zone and a running number in right ascension order within the zone. The present J2000 version gives the NPM1 positions transformed into the J2000 system and updated to the epoch 2000 using the NPM1 proper motions. The proper motions have been rotated into the J2000 coordinate system. The J2000 NPM1 Catalog is ordered in zones from +90 degrees to -23 degrees, and within each zone, the stars are sorted in right ascension order. To avoid "renaming" stars, the B1950 NPM1 "names" were retained, but the user must note that these no longer strictly reflect the declination zone and right ascension order in the J2000 NPM1 Catalog. The J2000 NPM1 Catalog is also available as 114 separate files, one for each declination zone from +90 degrees (z+90j) to -23 degrees (z-23j), from http://www.ucolick.org/~npm/NPM1/zones/ Each star's entry includes the absolute proper motion and blue magnitude. For 97% of the stars the color is also given. Other data given for each star are: the original mean epoch, a stellar class code, the number of NPM fields measured, and discrepancy flags for position, proper motion, and photometry. Finally, as an additional identification, the AGK3 (north) or SAO (south) number (if any) is given. The rms errors of the NPM absolute proper motions are about 0.5"/cent in each coordinate. The rms position errors at the catalog epoch 1950 average about 0.15" in each coordinate. The rms errors for the NPM photographic photometry average about 0.2 mag in B, and 0.15 mag in B-V. More complete information is available in the PostScript documentation for the 1993 (B1950) NPM1 Catalog (npm1b.ps), written by R.B. Hanson. We thank the National Science Foundation for its continued support of the NPM program. Recent work was supported by NSF grant AST-9530632. Current work is supported by NSF grant AST-9988105.
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