idlastro / Astronomical Utilities: TICS

[Source code]

NAME
TICS
PURPOSE
Compute a nice increment between tic marks for astronomical images.
EXPLANATION
For use in labelling a displayed image with right ascension
or declination axes.  An approximate distance between tic 
marks is input, and a new value is computed such that the 
distance between tic marks is in simple increments of the 
tic label values.
CALLING SEQUENCE
tics, radec_min, radec_max, numx, ticsize, incr, [ /RA ]
INPUTS
radec_min - minimum axis value (degrees)
radec_max - maximum axis value (degrees)
numx  - number of pixels in x direction
INPUT/OUTPUT
ticsize - distance between tic marks (pixels)
OUTPUTS
incr    - incremental value for tic labels (in minutes of 
        time for R.A., minutes of arc for dec.)
REVISON HISTORY
written by B. Pfarr, 4/14/87
Added some more tick precision (i.e. 1 & 2 seconds in case:) EWD May92
Added sub arcsecond tick precision   W. Landsman   May 2000
Plate scale off by 1 pixel  W. Landsman July 2004