[daip] RA-GLS question in aips

[Eric Greisen]

Sarma, Anuj writes:
 > Hello Eric,
 > 
 > I have a FITS dataset (from Nobeyama) whose header lists as RA-GLS. Is
 > there a simple way in aips that I can change this to RA-SIN? (I need to
 > do this so myriad-wip can work on it.) I've read the memo (46?) on
 > implementation, but haven't been able to transcribe this to an actual
 > command in aips.

the task to use is OHGEO  (or HGEOM)  which regrids the data from an
input image using the header of a sample image.  So read your image
in, copy it with SUBIM, use PUTHEAD to change the header to say
RA---SIN  and DEC--SIN and then run OHGEO.  It may take a couple tries
to get all the adverbs as you need.  NOte that -GLS projection can
cover large portions of the sky with little distortion while -SIN is
more limited.  This will work well for an image of at most a few
degrees on a side.

Note too that aips definition of GLS is more limited than the
definition in the new WCS standards.  Let us hope that the image is
within the simplistic aips regime.

Eric Greisen