The catalog header tells the program what to expect in each The first 28 bytes of each file contains the following information:
Integer*4 STAR0 Subtract from star number to get sequence number Integer*4 STAR1 First star number in file Integer*4 STARN Number of stars in file If negative, coordinates are J2000 instead of B1950 Integer*4 STNUM 0 if no star ID numbers are present 1 if star ID numbers are in catalog file 2 if star ID numbers are region nnnn (GSC) 3 if star ID numbers are region nnnnn (Tycho) 4 if star ID numbers are integer*4 not real*4 <0 No ID number, but object name of -STNUM characters at end of entry Integer*4 MPROP 0 if no proper motion is included 1 if proper motion is included 2 if radial velocity is included Integer*4 NMAG Number of magnitudes present (0-10) If negative, coordinates are J2000 instead of B1950 Integer*4 NBENT Number of bytes per star entryEach entry in the catalog contains the following information:
Real*4 XNO Catalog number of star [optional] Real*8 SRA0 B1950 Right Ascension (radians) Real*8 SDEC0 B1950 Declination (radians) Character*2 ISP Spectral type (2 characters) Integer*2 MAG(NMAG) V Magnitude * 100 [0-10 may be present] Real*4 XRPM R.A. proper motion (radians per year) [optional] Real*4 XDPM Dec. proper motion (radians per year) [optional] Real*8 SVEL Radial velocity in kilometers per second (optional) Character*(-STNUM) Object name [optional, precludes catalog number]Catalog numbers may be omitted to save space if they are monotonically increasing integers. Proper motions may be omitted if they are not known. There may be up to 10 magnitudes.