PPMS90K (S0): The 90,000 Stars Supplement To the PPM Catalog (19950216)
FILE:
Name Magnitude range Dec (2000) range #Stars
ppms90k.s0 6.8 <= mag <=13.0 -90 <= Dec <= +2 89676
CONTENTS: The 90,000 Stars Supplement To the PPM Catalog; 1993, Roeser et al.
DATASET: This file comes in HyperSky dataset S-27, version 19950216. Availability on HyperSky CD-ROM: Vol. 2 (1995)
DESCRIPTION: S. Roeser, U. Bastian, (1993) Astronomisches Rechen-Institut, Heidelberg; and A. Kuzmin, Sternberg Astronomical Institute, Moscow.
The PPM Star Catalog effectively has replaced the SAO & AGK3 catalogs by providing more precise astrometric data for more stars on the J2000/ FK5 coordinate system. Compared to the SAO Catalog, the improvement in precision is about a factor of 3 in the northern and a factor of 6 to 10 in the southern hemisphere. In addition, the number of stars is increased by about 50 percent.
The improvement over the SAO Catalog was made possible by the advent of large new catalogs of position measurements and by the inclusion of the century-old Astrographic Catalog (AC) into the derivation of proper motions. But the original PPM did not fully exploit all photographic position measurements available in the astronomical literature over the last 100 years. For example, The Astrographic Catalog contains some four million stars that are not included in the PPM. For most of these stars no precise modern-epoch position measurements exist. Thus it is not yet possible to derive proper motions with PPM quality for all AC stars. But among these 4 million stars there is a subset of some 100,000 stars from the Second Cape Photographic Catalog (CPC-2) that are not included in the PPM. The bulk of these stars constitute The 90,000 Stars (90K) Supplement to the PPM.
The CPC-2 is based on plates taken around 1966 in South Africa and measured in Great Britain, and provides 276,000 high-quality photographic star positions in the southern hemisphere. Of these 172,000 were already used in the construction of the PPM. The remaining 100,000 were not used because no precise later-epoch observations were available and because the PPM concept aimed at having more than two epochs per star.
The 90K Supplement provides J2000 positions and proper motions for most of the remaining 100,000 CPC-2 stars. The 90K Supplement was built in essentially the same way as PPM, but with only the CPC-2 and AC as observation catalogs. The CPC-2 was used as published, since it is based on the FK5 system. The AC was used in the fully reduced form produced for the original PPM project.
Positions and proper motions provided by the 90K Supplement are less precise than those in the southern part of PPM, but more precise than those of PPM north. Practical use of the 90K Supplement is perfectly the same as for the main parts of PPM.
The HyperSky file is based on the version of the catalog available at the U.S. National Space Sciences Data Center (NSSDC) as Astronomical Data Center (ADC) catalog #1208.
DATA: The HyperSky datafile contains the following data from the catalog. This information is essentially identical in content and presentation to the HyperSky information displayed for the main PPM, with the exception of the range of the PPM number (see below).
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.
MAG: the photographic magnitude, copied from AGK3. A 'V' in parentheses on the first comment indicates the magnitude is a photographic V magnitude copied from CPC-2 (see comment line note description below).
SP: the stellar spectral type, from the AGK3.
IDENTIFICATION: PPM number, ranging from 700001 to 789676. This 700K range permits the 90K Supplement stars to be easily distinguished from other PPM stars.
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.
pmd: Declination proper motion for epoch and equinox J2000.0, based on the FK5 system, given in seconds of arc per Julian year.
* Notes: At the end of the line containing pma and pmd, the letter V, in parentheses may appear, indicating the magnitude is a photographic V magnitude 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 90K Supplement provides the following useful catalog cross-identifications, which have been carried into the HyperSky file:
HD: Henry Draper star catalog
Durchmusterung catalog identification:
BD: Bonner Durchmusterung
CD: Cordoba Durchmusterung
CP: Cape Photographic Durchmusterung
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.
The 90,000 Stars Supplement is also described in a paper by Roeser, Bastian and Kuzmin in Astron. Astrophys. Suppl., 1994.