PPM (S0): Positions and Proper Motions (PPM) star catalog (19940518)
FILES:
Name Magnitude range Dec (2000) range #Stars
ppm60.s0 -1.5 <= mag <= 6.0 -90 <= Dec <= +90 4522
ppm6170.s0 6.1 <= mag <= 7.0 -90 <= Dec <= +90 7133
ppm7180n.s0 7.1 <= mag <= 8.0 0 <= Dec <= +90 10002
ppm7180s.s0 7.1 <= mag <= 8.0 -90 <= Dec < 0 14478
ppm8190n.s0 8.1 <= mag <= 9.0 +30 <= Dec <= +90 15438
ppm8190e.s0 8.1 <= mag <= 9.0 -30 < Dec < +30 38525
ppm8190s.s0 8.1 <= mag <= 9.0 -90 <= Dec <= -30 25827
ppm91n40.s0 13.5 <= mag <= 9.1 +40 <= Dec <= +90 47472
ppm91n20.s0 13.5 <= mag <= 9.1 +20 <= Dec < +40 39671
ppm91n00.s0 12.7 <= mag <= 9.1 0 <= Dec < +40 43827
ppm91s00.s0 12.4 <= mag <= 9.1 -20 < Dec < 0 45807
ppm91s20.s0 12.1 <= mag <= 9.1 -40 < Dec <= -20 40395
ppm91s40.s0 12.5 <= mag <= 9.1 -90 <= Dec <= -40 46134
CONTENTS: Positions and Proper Motions (PPM) Star Catalog
DATASET: These files come in HyperSky dataset S-18, version 19940518. Availability on HyperSky CD-ROM: Vol. 2 (1995)
DESCRIPTION: Roeser, S., Bastian, U. (1991): PPM Star Catalogue, Astronomisches Rechen-Institut, Heidelberg, Vols. I and II, printed by Spektrum Akademischer Verlag, Heidelberg.
The HyperSky files are based on machine-readable versions of the PPM catalog obtained from the NASA/GSFC Astronomical Data Center (ADC). The northern PPM data (-2.5 <= Dec < +90) was obtained from the (ADC) cd-rom "Selected Astronomical Catalogs", Volume 1. However, because cd-rom southern data was only preliminary, more recent southern and supplementary PPM data was obtained from ADC in May 1994 through alternate channels.
The HyperSky PPM files contain 181731 stars from the northern PPM catalog, 197179 stars from the southern PPM catalog, and 321 stars from the supplementary list, for a total of 379231 stars. However, because the supplementary list contains various bright stars included only for completeness, its stars are distinguished by numbers starting with 400000. Thus actual PPM numbers extend from 1 to 378910, and 400000 to 400321.
The purpose of the PPM is to provide a convenient, dense and accurate net of astrometric reference stars. The net is designed to represent as closely as possible the IAU (1976) cooordinate system on the sky, as defined by the FK5 star catalogue (Frick et al., 1988). Thus, the PPM is an extension of the FK5 system to higher star densities and fainter magnitudes.
The PPM can be considered a replacement of two preceding astrometric catalogs which served a similar purpose: AGK3 and the SAO Catalog. In contrast to the PPM, these older catalogs are based on (1) the now obsolete FK4 system of positions and proper motions, and (2) only two position measures per star.
Regarding completeness, the intent of the PPM supplemental list is to render the PPM complete to magnitude V=7.5. For fainter magnitudes, the supplemental list documentation states that,
"... of the perhaps 20 000 stars between V=7.5 and V=8.5 only a few hundred are missing from PPM. So, the combined PPM can be considered as practically complete to at least V=8.5. In photographic magnitudes this corresponds to roughly 9 mag."
DATA:
The HyperSky datafiles contain the following data from the PPM catalog:
POSITION: Right Ascension and Declination are the catalog epoch and equinox J2000 values, stored in the HyperSky files to an accuracy of 0.1m in RA and 1 arc second in Declination. For FK5 stars the original FK5 values are used. FK5 stars are indicated by an 'F 'in parentheses on the first comment line (see comment line note descriptions below).
MAG: Either the photographic magnitude, copied from AGK3; or the visual magnitude for FK5 stars, copied from FK5. A 'V' in parentheses on the first comment indicates the magnitude is a photographic V magnitude copied from CPC-2 (see comment line note descriptions below).
SP: the stellar spectral type, copied either from AGK3 or, for FK5 stars, from FK5.
IDENTIFICATION: PPM number
COMMENTS: The comment lines contain the following information, provided if available for each PPM star:
* Proper motion values
pma: RA proper motion for epoch and equinox J2000.0, based on the FK5 system, and given in seconds of time per Julian year. For FK5 stars rounded FK5 data are given.
pmd: Declination proper motion for epoch and equinox J2000.0, based on the FK5 system, given in seconds of arc per Julian year. For FK5 stars rounded FK5 data are given.
* Notes: At the end of the line containing pma and pmd, one or more letters in parentheses are encoded notes on the star. Notes P, C and D mark objects that should preferably not be used as astrometric reference stars. The following letters may appear:
C - a critical remark on this object is given in the PPM "List of Critical Remarks" (see PPM if interested). The star should not be used as astrometric reference star.
D - double star, preferably not to be used as astrometric reference star.
H - member of the High-Precision Subset (HPS) of PPM.
P - problem case, preferably not to be used as astrometric reference star.
F - member of FK5, high precision stars, mostly very bright stars.
R - a remark on this star is given in the PPM "List of Remarks on
Individual Stars" (see PPM if interested).
V - the magnitude is a photographic V magnitude copied from the Second Cape Photographic Catalogue (Zacharias, N., de Vegt, C., Nicholson, W., Penston, M., 1992: Astron. Astrophys. 254, 394.)
* Catalog cross-identifications. The PPM provides several useful catalog cross-identifications, which have been carried into the HyperSky files. These catalogs are identified by their prefixes below:
SAO: Smithsonian Astrophysical Observatory Star Catalog
HD: Henry Draper star catalog
Durchmusterung catalog identification:
BD: Bonner Durchmusterung
CD: Cordoba Durchmusterung
CP: Cape Photographic Durchmusterung
A3: AGK3 (Third Astrographic Catalog)
Users should note that the 321 stars in the PPM supplementary list, though all brighter than 8th magnitude, were NOT provided with catalog cross-references. As indicated above, these stars are all flagged by PPM numbers > = 400000.
REFERENCE
Bastian, U., Roeser, S., et al., 1993, PPM Star Catalogue, Vols. III and IV, positions and proper motions of 197179 stars south of -2.5 degrees declination. Astronomisches Rechen-Institut, Heidelberg. Spektrum Akademischer Verlag, Heidelberg, Berlin, New York, 1993.