================================================================================ Lick Northern Proper Motion Program: NPM2 Catalog R.B. Hanson, A.R. Klemola, B.F. Jones (UCO/Lick Observatory) and D.G. Monet (US Naval Observatory, Flagstaff) UCO/Lick Observatory, University of California, Santa Cruz CA 95064 USA May 2003 http://www.ucolick.org/~npm/NPM2/ ================================================================================ The NPM2 Catalog is the second part of the Lick Northern Proper Motion (NPM) program to measure absolute proper motions, on an inertial system defined by distant galaxies, for nearly 400,000 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 NPM2 Catalog covers the 28% of the northern sky lying near the plane of the the Milky Way and contains some 232,000 stars in the 347 NPM fields remaining after the 1993 NPM1 Catalog (149,000 stars in 899 fields away from the Milky Way). Each NPM field was photographed with the 51 cm Carnegie Double Astrograph 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. For NPM2, the plates were scanned by the Precision Measuring Machine (PMM) at the US Naval Observatory, Flagstaff. From the PMM scans, 120,000 faint (B > 14) stars were chosen anonymously for the NPM astrometric reductions and for statistical studies of stellar motions. The NPM2 catalog also contains 92,000 bright (B < 14) positional reference stars, mostly from the Tycho-2 Catalogue, and 35,000 stars chosen for astronomical interest from Klemola's "Lick Input Catalog of Special Stars". (These categories overlap.) Details of the NPM2 star selection, data reductions, and catalog compilation will be presented in a paper being prepared for the Astronomical Journal. The completed version of the NPM2 Catalog totals 232,062 stars from all 347 NPM2 fields; it supersedes the September 2002 preliminary version (295 fields). Together with the NPM1 Catalog (J2000 version at http://www.ucolick.org/~npm/NPM1/) the NPM2 Catalog completes the Lick Northern Proper Motion program after more than a half-century of work by three generations of Lick Observatory astronomers. The NPM2 catalog gives J2000 positions computed for the catalog epoch 2000, and is in the form of 108 one-degree declination zone files (e.g. z+83n) from +83 degrees to -23 degrees. Following the convention of the NPM1 catalog, each NPM2 star has an NPM2 "name" (e.g. +83.0001) reflecting the declination zone and a running number in right ascension order within the zone. Each star's entry includes the absolute proper motion and blue (B) magnitude. For 98.5% of the stars the B-V color is also given. Other data given for each star are: the original mean epoch, a stellar class code, the number of NPM fields on which the star was measured, and discrepancy flags for position, proper motion, and photometry. Tycho-2 numbers are given for the primary positional reference stars (40% of NPM2); for these stars the Tycho-2 B,V photometry, transformed to Johnson B and B-V, has been averaged with the NPM2 photographic photometry, with appropriate weights. ACRS and Hipparcos numbers are also given for NPM2 stars selected from those catalogs. The RMS precision of the NPM2 individual proper motions is about 0.6"/cent (6 mas/yr) in each coordinate, comparable to the NPM1 errors. The NPM2 relative proper motions in each field were reduced to absolute (ICRS system) using an average of 370 Tycho-2 stars per NPM2 field. Magnitude-dependent systematic errors for the brightest (8 < B < 12) NPM2 stars were removed in the same reductions. The RMS accuracy of the proper motion zero point in each field is about 0.05"/cent (0.5 mas/yr) in each coordinate. The RMS position errors at the NPM2 catalog epoch 2000 average about 0.2" (200 mas) in each coordinate, due mostly to the accumulated proper motion error from the original plate epochs (average 1968) to 2000. The pure positional errors at the original epochs average 0.08" (80 mas) in each coordinate. The RMS errors for the NPM photographic photometry average about 0.18 mag in B, and 0.20 mag in B-V. We thank the National Science Foundation for its long-term support of the NPM program. The NPM2 phase was supported by NSF grants AST-9530632 and AST-9988105. We thank the Yale Southern Proper Motion group (W. van Altena, I. Platais, and T. Girard) for their help in developing software to process the PMM plate scans. -------------------------------------------------------------------------------- Byte-by-byte Description of NPM2 declination zone file -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 A8 --- Name NPM2 star "name" made of: Byte 1 : Sign of J2000 declination Bytes 2-3: J2000 Declination zone Bytes 4-8: Running number in this J2000 declination zone 9- 11 3X 12- 13 I2 h RAh Right Ascension J2000 (hours) 14 1X 15- 16 I2 min RAm Right Ascension J2000 (minutes) 17 1X 18- 23 F6.3 s RAs Right Ascension J2000 (seconds) 24- 25 2X 26 A1 --- DE- Declination J2000 (sign) 27- 28 I2 deg DEd Declination J2000 (degrees) 29 1X 30- 31 I2 arcmin DEm Declination J2000 (minutes) 32 1X 33- 37 F5.2 arcsec DEs Declination J2000 (seconds) 38- 45 F8.2 arcsec/hyr pmRA Absolute proper motion RA (in "/century) 46- 53 F8.2 arcsec/hyr pmDE Absolute proper motion Dec. 54- 55 2X 56- 61 F6.2 mag B *B magnitude 62- 67 F6.2 mag B-V *?=-9.99 B-V color 68- 70 3X 71- 75 F5.2 yr Epoch Original mean epoch of position (-1900) 76- 77 2X 78 I1 --- class *[1,7] Code for class of star 79- 80 2X 81 I1 --- nfields Number of NPM fields on which star was measured 82 1X 83 I1 --- ips *Discrepancy flag Position 84 I1 --- ipm *Discrepancy flag Proper Motion 85 I1 --- ibv *Discrepancy flag Photometry 86- 87 2X 88- 99 A12 --- TYCHO Tycho-2 catalog identification 100-101 2X 102-107 A6 --- ACRS ACRS catalog identification 108-109 2X 110-115 A6 --- HIPP Hipparcos catalog identification -------------------------------------------------------------------------------- Note on B: NPM2 photographic photometry, unless star has Tycho-2 identification; then weighted mean of (1) NPM2 magnitude and (2) Tycho-2 blue magnitude, transformed to Johnson B. Note on B-V: NPM2 photographic photometry (= -9.99 if no data), unless star has Tycho-2 identification; then weighted mean of (1) NPM2 color and (2) Tycho-2 color, transformed to Johnson B-V. Note on class: The code is a sum of the following numbers, if applicable. +1 if anonymous star (faint or bright) +2 if astrometric catalog star (Tycho-2, ACRS, or Hipparcos) +4 if other star (Lick Input Catalog) Note on ips, ipm and ibv: Flags for large residuals for stars with multiple measures: ---------------------------------------------------------- Position Proper Motion Photometry ---------------------------------------------------------- Flag=0 O.K. O.K. O.K. Flag=1 R.A. R.A. B Flag=2 Dec. Dec. B - V Flag=3 Both Both Both ---------------------------------------------------------- Limits 0.3 arcsec 2.0 arcsec/cent 0.5 mag (at 1968) ================================================================================ Robert B. Hanson 2003 May 23