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.help galactic Oct87 noao.astutil
.ih
NAME
galactic -- convert between equatorial and galactic coordinates
.ih
USAGE
galactic files
.ih
PARAMETERS
.ls files
The name of a file (or a file list or template) containing the coordinates
to be converted.
.le
.ls in_coords = "equatorial"
Type of input coordinates. May be either "equatorial" (RA and DEC) or
"galactic" (l and b).
.le
.ls print_coords = yes
If \fBprint_coords\fR = yes, the RA, DEC and epoch (as well as lII and bII)
will be listed on the output file.
.le
.ih
DESCRIPTION
Program \fBgalactic\fR is used to convert between equatorial and
galactic coordinates. It converts in either direction based on the
specified input coordinates. Coordinates are read from the input file
as RA and DEC or galactic longitude and latitude pairs, one pair per
input line. Each coordinate pair may optionally be followed by the
epoch of the equatorial coordinates, in which case the coordinates are
precessed to 1950.0 (the epoch of definition for the galactic center)
before conversion for equatorial to galactic or to the specified epoch
for galactic to equatorial. Coordinates may be entered in either
decimal or sexagesimal notation.
.ih
EXAMPLES
1. Convert the given RA and DEC coordinates to galactic coordinates. When
the epoch is specified as other than 1950.0, precess before converting.
The lines input by the user are marked:
.nf
cl> galactic STDIN [input]
12:30:10.12 10:18:27.5 1930. [input]
12:30:10.12 10:18:27.5 1930.00 288.4695 72.2884
12:30 10:18 [input]
12:30:00.00 10:18:00.0 1950.00 287.4598 72.3202
12.5 10:18 [input]
12:30:00.00 10:18:00.0 1950.00 287.4598 72.3202
(eof=<ctrl/z>) [input]
.fi
2. The following is equivalent, except that coordinate input is taken from
the file "coords", rather than from the terminal:
.nf
cl> galactic coords [input]
12:30:10.12 10:18:27.5 1930.00 288.4695 72.2884
12:30:00.00 10:18:00.0 1950.00 287.4598 72.3202
12:30:00.00 10:18:00.0 1950.00 287.4598 72.3202
.fi
3. If image headers contain the coordinates, in this case RA, DEC, and EPOCH,
then one can get the galactic coordinates for the image by:
cl> hselect *.imh ra,dec,epoch yes | galactic STDIN
(Consult the help for the task \fBhselect\fR for information about selecting
fields from image headers.)
.endhelp
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