;+
;    Procedure BCS_LOCATE to suggest a location of a flare (north or south of
;    projected sun centre) based on the BCS lines positions and the old
;    calibration of bin number versus flare position
;    NB this does not take account of any pointing offsets.
;
; Use:
;           must have used GS, GS_CUR and GS_SP first, then...
;
;           IDL> .run bcs_locate
;                            
;                 use cursor to define region of resonance lines in succession
;
;
;    CDP June 92
;
;-

!p.multi=[0,0,3]
pos = fltarr(3)
loc = fltarr(3)
;
;  fits from old data, could be updated
;
coff = [[-3140.88,-1151.79,-1593.16],[21.32,25.927,47.17]]

tit = ['Mean FeXXV spectrum','Mean CaXIX spectrum','Mean SXV   spectrum']
print,'Use cursor to define resonance line window'
for kk = 0,2 do begin
   if kk eq 0 then  f = gsp(256:511)
   if kk eq 1 then  f = gsp(512:638)
   if kk eq 2 then  f = gsp(639:766)
   !mtitle = tit(kk)
   plot,f,psym=10,charsize=2
   nfit = 0
   cursor,s1,qq,3,/data
   oplot,[s1,s1],[0,1000]
   cursor,s2,qq,3,/data
   oplot,[s2,s2],[0,1000]
   if s1 gt s2 then begin
      temp = s1
      s1 = s2
      s2 = temp
   endif
   nfit = [fix(s1),fix(s2)]
   x    = findgen(nfit(1)-nfit(0)+1) + nfit(0)
   yfit = findgen(nfit(1)-nfit(0)+1)
   a    = fltarr(6)
   y = f(nfit(0):nfit(1))
   a(0) = max(y)
   p = where(y eq a(0))
   a(1) = p(0)  
   a(2) = 3.0
   a(3) = y(n_elements(y)-1)
   a(4) = 0.0
   a(5) = 0.0
   yfit = gaussfit(x,y,a)
   oplot,x,yfit,psym=-3,thick=2
   pos(kk) = a(1)
   !linetype = 2
   oplot,[pos(kk),pos(kk)],[0,1000]
   !linetype = 0
   loc(kk) = (coff(kk,0) + coff(kk,1)*pos(kk))/60.
   if loc(kk) gt 0.0 then begin
      print,'Likely location is ',loc(kk),' North of sun centre',$
             format='(a,f5.1,a)'
   endif else begin
      print,'Likely location is ',abs(loc(kk)),' South of sun centre',$
             format='(a,f5.1,a)'
   endelse

endfor
print,' '
meanloc = total(loc)/3.0
if meanloc gt 0.0 then begin
   print,'Mean location is ',meanloc,' North of sun centre',$
          format='(a,f5.1,a)'
endif else begin
   print,'Mean location is ',abs(meanloc),' South of sun centre',$
          format='(a,f5.1,a)'
endelse
!p.multi = 0
!mtitle = ' '
end