function sxt_lcur, struct, max=max, qstop=qstop
;
;+
;NAME:
;	sxt_lcur
;PURPOSE:
;	To return a vector giving DN/sec/FR pixel
;CALLING SEQUENCE:
;	y = sxt_lcur(roadmap)
;	plot, sxtp, sxt_lcur(sxtp, filtb=2)
;INPUT:
;	struct	- The roadmap or observing log
;		  FUTURE - can pass the index
;OPTIONAL KEYWORD INPUT:
;	max	- If set, use "img_max" instead of "img_avg"
;OUTPUT:
;	Returns a floating vector the same length as the input
;	structure with DN/sec/FR pixel.
;HISTORY:
;	Written 7-Jul-92 by M.Morrison
;-
;
if (keyword_set(max)) then dn = struct.img_max else dn = struct.img_avg
dn = dn*4.
;
expos = gt_dpe(struct, /conv)/1000.	;exposure in seconds
npix = ( 2^gt_res(struct) )^2
;
out = dn/expos/npix
;
if (keyword_set(qstop)) then stop
return, out
end