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