Primary FITS Headers: headfits.pro

The primary FITS header can be accessed with the headfits.pro function. Individual keywords can be accessed with sxpar.pro as below:

IDL> hdr=headfits('filename.fit')

IDL> print,hdr

SIMPLE  =                      T / file does conform to FITS standard

...

IDL> focus = sxpar(hdr,'FOCUS',count=count)     ;count returns 0 if the keyword is not found

IDL>