RFITS reads a standard format FITS file by typing:
IDL> img = rfits(infil, header=header)
where img is the image, infil is the input file name, and 
is
the string array with the data header in it. It is possible to use
the 
option to convert the data into some physical units. For
example, the magnetogram data would be converted to gauss.
IDL> img = rfits('/yd0/gbo92_37/gkm920907.1442', head=head, /scale)