wlandsman / IDLAstro

Astronomy related procedures in the commercial IDL language
https://asd.gsfc.nasa.gov/archive/idlastro/
BSD 2-Clause "Simplified" License
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imcountour.pro frames unusable/wrong results for larger sky fields and other than TAN projection #36

Open WBeckerGitHub opened 1 year ago

WBeckerGitHub commented 1 year ago

imcontour .pro uses ticlabels.pro which has the statement:

; RESTRICTIONS: ; Invalid for wide field (> 2 degree) images since it assumes that a ; fixed interval in Y (or X) corresponds to a fixed interval in Dec ; (or RA)

which explains why imcontour.pro gives wrong labeling and tick marks when using a larger sky field... Also, when using SIN projection rather than TAN projections the routine gives wrong results and coordinates drawn around an image are not correct. If the image is converted e.g. from SIN to TAN projection by using e.g.

remap -w TAN -o output_TAN.fits Input_SIN.fits

If someone has a routine which does it better than ticlabels.pro please share...