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Equinox

Because precession is a large effect, we must know the equinox to which these coordinates refer. Although this is usually a constant for a whole table, and so might be stored in a descriptor, observers may want to use lists of program stars compiled from heterogeneous sources. Therefore, the year of the equinox must be stored in a separate column of Real*4 values, with the label EQUINOX. This column is easily created for a star catalog with a single equinox date using the COMPUTE/TABLE tablename :EQUINOX = year command. A format of F7.1 is satisfactory.


 
Table: Columns for star-catalog table files
Column Label Contents Units Variable Type Format Req'd?
OBJECT Object name   C*32 string A32 Y
RA Right Ascension degrees R*4 real R11.6 Y
DEC Declination degrees R*4 real s12.6 Y
EQUINOX Equinox date years R*4 real F7.1 Y
MUALPHA Annual p.m. in R.A. sec/y R*4 real F7.4 N
MUDELTA Annual p.m. in Dec. arcsec/y R*4 real F7.3 N
EPOCH Position date years R*4 real F5.0 N
SPTYPE Spectral type   C*15 string A14 N
MAG Approx. mag.   C*11 string A11 N
COMMENT Comment   C*32 string A32 N
 


next up previous contents
Next: Optional stellar data Up: Required stellar data Previous: Declination
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1999-06-15