FUNCTION getlims,nimages,utsec,start=start,finish=finish

lims=INTARR(2)

IF KEYWORD_SET(start) THEN BEGIN
    sstart=SIZE(start)
    IF sstart(0) EQ 0 THEN startut=start $
	ELSE BEGIN
	IF sstart(1) LT 3 THEN start=INTARR(3)+start
	startut=TOTAL([3600.,60.,1.]*start)
	ENDELSE
    after=WHERE(utsec GT startut,nafter)
    IF nafter GT 0 THEN lims(0)=MIN(after) ELSE $
	MESSAGE,'No data after '+STRTRIM(startut,2)+' s UT!'
    ENDIF ELSE lims(0)=0

IF KEYWORD_SET(finish) THEN BEGIN
    sfinish=SIZE(finish)
    IF sfinish(0) EQ 0 THEN finishut=finish $
	ELSE BEGIN
	IF sfinish(1) LT 3 THEN finish=INTARR(3)+finish
	finishut=TOTAL([3600.,60.,1.]*finish)
	ENDELSE
    before=WHERE(utsec LT finishut,nbefore)
    IF nbefore GT 0 THEN lims(1)=MAX(before) ELSE $
	MESSAGE,'No data before '+STRTRIM(finishut,2)+' s UT!'
    ENDIF ELSE lims(1)=nimages-1

RETURN,lims
END