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NSSDC/WDC-A-R&S 82-20 DOCUMENTATION FOR THE MACHINE-READABLE VERSION OF THE GENERAL CATALOGUE OF TRIGONOMETRIC STELLAR PARALLAXES AND SUPPLEMENT Wayne H. Warren Jr. June 1982 National Space Science Data Center (NSSDC)/ World Data Center A for Rockets and Satellites (WDC-A-R&S) National Aeronautics and Space Administration Goddard Space Flight Center Greenbelt, Maryland 20771 TABLE OF CONTENTS Section 1 - INTRODUCTION AND SOURCE REFERENCE ........................ 1-1 Section 2 - TAPE CONTENTS ............................................ 2-1 Section 3 - TAPE CHARACTERISTICS ..................................... 3-1 Section 4 - REMARKS, MODIFICATIONS, ACKNOWLEDGMENTS AND REFERENCES ... 4-1 Table 1 - Tape Contents .................................................. 2-1 2 - Tape Characteristics ........................................... 3-1 iii SECTION 1 - INTRODUCTION AND SOURCE REFERENCE The General Catalogue of Trigonometric Stellar Parallaxes (Jenkins 1963) is a compilation of only trigonometric parallaxes determined from photographic plates. The 1963 edition of the catalogue is a reprint of an earlier edition (Jenkins 1952) containing parallax values received before June 1950, with the addition of a 1963 supplement containing all determinations available in December 1962. The machine-readable version of the catalogue contains the basic data of the 1952 edition, with the new absolute parallax values in Section I of the 1963 Supplement, plus the new stars in Section II. The miscellaneous corrections listed in Section III of the 1963 Supplement have been made. The data and remarks on the right-hand pages of the published catalogue are not included in this machine-readable version. This document describes the machine-readable version of the catalogue as distributed by the Astronomical Data Center. It is intended to enable users to read and process the data without problems and guesswork. The source reference should be consulted for details concerning the compilation of the main catalogue and supplement, the probable errors, and the weighting system used to combine determinations from different observatories. A copy of this document should be supplied with any machine-readable copy of the catalogue. SOURCE REFERENCE Jenkins, L. F. 1963, General Catalogue of Trigonometric Stellar Parallaxes (New Haven: Yale University Observatory). 1-1 SECTION 2 - TAPE CONTENTS A byte-by-byte description of the contents of the General Catalogue of Trigonometric Stellar Parallaxes is given in Table 1. The suggested format specifications are for FORTRAN formatted read statements and can be modified depending upon individual programming and processing requirements. Since data fields contain blanks where data are absent, care must be exercised when processing the catalogue for search or computational purposes, particularly for data which can have valid zero values. In this case, it is safest to buffer the data in or read them with character (A) format specifications and check for blanks before processing. Note that the additional decimal place for each star included from the Supplement is located at the end of a logical record rather than immediately following the star number. Alternate format specifications are given in parentheses. Table 1. Tape Contents. General Catalogue of Trigonometric Stellar Parallaxes. Suggested Byte(s) Units Format Description 1- 4 --- I4 Sequential number by which the catalogue is ordered. Although the numbering system initially corresponded strictly to increasing right ascension, several RA corrections have destroyed the strict correspondence. There are also exceptions to the general rule of North to South ordering for stars having the same RA. 5-12 --- A8 Durchmusterung number (BD for zones +89 to -22, CD for zones -23 to -51, CPD for zones -52 to -89). The sign is always in byte 5, the zone in bytes 6-7, and the number in bytes 8-12. The field is blank when no DM number is present. 13 --- A1 Suffix for DM number. Field contains a lower case "a" for two supplemental BD stars (Nos. 1624 and 4098 [Barnard's Star]) or an asterisk if a CD number is given south of the -51 zone (or CPD north of the zone), etc. Blank if no suffix present. 14-15 hours I2 Right ascension for equinox 1900. 16-18 min F3.1 Right ascension 2-1 Table 1. (continued) Suggested Byte(s) Units Format Description 19-21 deg I3 (A1,I2) Declination for equinox 1900. Sign always in byte 18. 22-23 arcmin I2 Declination 24-27 mag F4.1 (A4) Visual or photographic magnitude (see byte 27). All actual magnitude data con- tain either a positive or negative sign in byte 23. If a magnitude is given as "var" or "nova" in the published catalogue, then byte 23 is blank and the value is set to 99.9 (nines in bytes 24-26). Note that lower precision data are indicated by the presence of a blank in byte 26. 28 --- A1 Magnitude code (V for visual, P for photographic, blank for 999 magnitudes). 29-31 --- A3 Spectral type from the Henry Draper Cata- logue (HD). For many stars fainter than magnitude 6.5, Mount Wilson spectral types are reported; additional types were sup- plied by G. P. Kuiper and A. N. Vyssotsky. Blank if no data present. 32-37 --- I6 (A6) HD number, otherwise blank. 38 --- A1 HD code. The digit 9 denotes that HD and HD+1 are taken together (when the entry represents two HD numbers, the HD number given is always the lower of the two). Otherwise zero. 39-47 --- 9A1 (A9) Source catalogues for proper motions following. The catalogue abbreviation (GC - Boss 1937, CI18 - Porter et al. 1915, CI20 - Porter et al. 1930, LT, LTT - Luyten 1957, 1961, 1962) and cata- logue number are given. Blank if no data. 48-52 arcsec F5.3 Proper motion in right ascension. Sign always in byte 46. Blank if no data. 2-2 Table 1. (concluded) Suggested Byte(s) Units Format Description 53-58 arcsec F6.3 Proper motion in declination. Sign always in byte 51. Blank if no data. Note: The accuracy of the proper-motion data is indicated by the precision to which the data are reported, viz., for lower accuracy values, bytes 50 and 56 are blank. For GC stars, the motions are reported to a precision of three decimal places. For the Cincinnati and other catalogues, the motions are given to varying accuracy. When only the proper motion in right ascension is present, it has been determined from the parallax solution. When only the total proper motion is given in the published catalogue, the proper-motion fields are blank. 59-62 arcsec F4.3 The adjusted absolute trigonometric parallax. The field is blank in cases where the same star has multiple records and the record is not the first (see byte 63). 63-64 arcsec F2.3 The adjusted probable error of the parallax. Blank when the parallax field is blank. 65 --- I1 When there are multiple records in the catalogue for additional components of multiple stars, each component (including the first) is numbered sequentially (1, 2, ...) in this byte. 66 --- I1 Stars from the supplement are numbered with the 1952 catalogue number after which the star has been inserted (in R.A. order) plus an additional decimal place, e.g. star 16.1 has been inserted after star 16. Byte 64 contains the additional digit. If the catalogue is to be sorted back to the original order after being ordered in some other way, this byte should be the secondary sort field. Blank for stars in the original 1952 edition. 2-3 SECTION 3 - TAPE CHARACTERISTICS The information contained in Table 2 is sufficient for a user to describe the indigenous characteristics of the machine-readable General Catalogue of Trigonometric Stellar Parallaxes to a computer. Information easily varied from installation to installation, such as block size (physical record length), blocking factor (number of logical records per physical record), total number of blocks, tape density, number of tracks, and internal coding (EBCDIC, ASCII, etc.) is not included. This information should always be supplied if secondary copies are transmitted to other users or installations. Table 2. Tape Characteristics. General Catalogue of Trigonometric Stellar Parallaxes. NUMBER OF FILES ................................................... 1 LOGICAL RECORD LENGTH (BYTES) ..................................... 66 RECORD FORMAT ..................................................... FB* TOTAL NUMBER OF LOGICAL RECORDS ................................... 6675 * Fixed block length (last block may be short) 3-1 SECTION 4 - REMARKS, MODIFICATIONS, ACKNOWLEDGMENTS AND REFERENCES The General Catalogue of Trigonometric Stellar Parallaxes was received on magnetic tape from Dr. P. K. Seidelmann of the U.S. Naval Obseratory (USNO) on 5 May 1982. The Supplement stars had been merged into the data file after being punched at USNO. The following modifications were made to the data file in order to make it easier to process and more uniform with respect to other machine-readable catalogues: 1. Preceding zeroes were removed from all sequential catalogue numbers. 2. Blank bytes in the proper-motion and magnitude code fields were filled with minus signs. These were changed to blanks where appropriate. 3. The catalogue had been recorded in O26 character code. It was converted to O29 by changing all & characters to + signs. 4. The 999 digits were added to the magnitude fields previously containing the words "var" and "nova." (The fields were previously blank.) 5. The declination proper motion data field for star 4098 (originally bytes 51-55) was coded A027 to represent +1027 (= +10.27) because the field was too small. The data field was therefore increased from five to six bytes (now 53-58) and the correct value inserted. 6. The logical record length was changed from 80 bytes to 66 bytes. Bytes were added to accommodate the DM suffix (byte 13) and the HD code (byte 38). Individual corrections were made for stars 60 (data misalignment), 4494 record 2 (photographic magnitude omitted--added from published catalogue), 5470 (R.A. changed from 22+20 to 22320) and 96.1 (spurious "O" removed from spectral type). In addition, corrections to fourteen stars, kindly supplied by Dr. W. F. van Altena of Yale University, to whom the catalogue had also been sent, were made. The corrections involved data misalignment, incorrect Supplement digits, and record reversal (stars 298.2, 386.2, 1152.1, 1213.1, 1216.2, 1393.2, 1470.1, 1476.1, 1477.1, 1794.2, 3198.2, 3249.0, 3251.0 and 3256.2, where the zero indicates a non-Supplement star). Corrections by Hoffleit (1982) were also made; the latter corrections included the deletion of two duplicate entries (4728 and 4426.1). ACKNOWLEDGMENTS Appreciation is expressed to P. K. Seidelmann for supplying the updated version of the machine-readable catalogue, to W. F. van Altena for transmitting the corrections found at Yale, and to D. Hoffleit for checking some of the corrections in her published list and supplying additional corrections discovered more recently. 4-1 REFERENCES Boss, B. 1937, General Catalogue of 33342 Stars for the Epoch 1950 (Washington: Carnegie Institution of Washington). Hoffleit, D. 1982, CDS Inform. Bull. No. 22, p. 112. Jenkins, L. F., 1952, 1963, General Catalogue of Trigonometric Stellar Parallaxes (New Haven: Yale University Observatory). Luyten, W. J. 1957, A Catalogue of 9867 Stars in the Southern Hemisphere with Proper Motions Exceeding 0.2" Annually (Minneapolis: Lund Press). Luyten, W. J. 1961, A Catalogue of 7127 Stars in the Northern Hemisphere with Proper Motions Exceeding 0.2" Annually (LTT 10001-17027) (Minneapolis: Lund Press). Luyten, W. J. 1962, First Supplement to the LTT Catalogues (LTT 17028-18635) (Minneapolis: Lund Press). Porter, J. G., Yowell, E. I. and Smith, E. 1915, Publ. Cincinnati Obs. 18; 1930, 30. 4-2