;+
; function pickfits,header,instrument=instrument,filenames=filesnames
; 
; NAME: pickfits
; PURPOSE:
; 	pick one or more fits files using the GUI and then load them.
; NOTES:
; 	returns the images and headers as multidimensional arrays, if
; 	you select more than one file.
;
; 	This is basically just a GUI frontend to fitsloader.pro, which handles
; 	any scaling rules for coadds or nreads for different images.
;
; INPUTS:
;       filenames	a list of filenames to load. If not supplied, then
;       			you will be prompted with a file selection dialog box
;       
; KEYWORDS:
;       instrument	the name of the instrument these files are from; passed 
;               	to fitsloader.pro
;       
; OUTPUTS:
;       returns the selected image(s) as a 2d image or 3d cube, as appropriate
;       
;       headers		returns the fits headers for the image(s) as a 1d 
;       			or 2d string array, as appropriate.
;
; HISTORY:
;   Began 2002-10-30 23:02:46 by Marshall Perrin 
;-

function pickfits,outheader,instrument=instrument,filenames=filesnames

	if not(keyword_set(filenames)) then begin
		filenames = dialog_pickfile(filter="*.fits",/multiple_files,/must_exist,$
			title="Select FITS file(s) to load.")
	endif
	if filenames[0] eq "" then return,!values.f_nan

	; use fitsloader to do all the work.
	if n_elements(filenames) gt 0 then begin
		if not(keyword_set(instrument)) then begin
			header0 = headfits(filenames[0])
			instrument = sxpar(header0,"INSTRUME")
			if instrument eq 'IRCAL   ' then instrument="IRCAL"
			; add other checks here?
		endif

		fitsloader,[0],outimage,outheader,imlist=filenames,instrument=instrument
		return,outimage
	endif

	; nothing valid selected....
	return,!values.f_nan
end