The routine GT_CENTER will allow a user to determine the coordinates of the
center of a PFI image.
The output from this routine can be the location of the center of
the field of view in (a) full resolution IDL pixels coordinates
, (b) heliocentric,
(c) the angle E/W and N/S from the center of the sun
in arcseconds, or (d) the HXT equivalent pixel coordinates.
If the user has the index available in the variable
index, then he can use the following commands (these commands will
also work for the roadmap structure)
IDL> pix = gt_center(index)
IDL> helio = gt_center(index, /helio)
IDL> helio = gt_center(index, /helio, /string)
IDL> helio = gt_center(index, /helio, /cmd)
IDL> ang = gt_center(index)
The default is to read the ATT S/C pointing database for the true sun center location. It is possible to use the commanded S/C pointing information by using the /CMD option, which is much faster and only of slightly reduced accuracy. The /STRING option will print the heliocentric coordinates in the format ``N23E45''.