A quick note on gethead of WCSTools – as I have needed many times (but obviously not that many to remember it!).
Rather straightforward use: gethead HEADER_KEY image.fits
(as simple as possibly!)
If HEADER_KEY contains empty spaces then use double quotes, e.g. “HIERARCH TEL AIRM END”.
Reminder: you have to have installed already the WCSTools! (See the “Installing WCSTools” for this.)
[Ref: WCSTools – gethead: http://tdc-www.harvard.edu/software/wcstools/gethead/gethead.html ]