function two_src_visibility1,flux,area,x,y,sc,pa=PA,PLOT=plot

; PURPOSE: returns  complex visibility of two sources on ONE RHESSI uvcircle

; INPUTS:
; Flux = float(2) = flux vector for two sources
; Area = float(2) = area vector for two sources 
;      = !pi*[a1^2,a2^2] where a1, a2 are Gaussian widths in asec
; x = float(2) = x coordinate of two sources relative to map center (asec)
; y = float(2) = y coordinate of two sources relative to map center (asec)
; sc = scalar 1 to 9
;
;OPTIONAL INPUTS:
; pa = vector of position angles (defaults to 32 values on 0 to 2*!pi) 
; /plot to plot the amplitude profile
;
; OUTPUT:
;  complex visibility of two sources
;;OPTIONAL INPUTS:
; ejs dec 12, 2006

default,pa,findgen(32)*!pi/32   ; from 0 to 180 degrees

pitch=((hsi_grid_parameters()).pitch)[sc-1]
kx=cos(pa) # (1/pitch)
ky=sin(pa) # (1/pitch)
k=sqrt(kx^2+ky^2)

x1=x-mean(x)  ; shift to center of sources
y1=y-mean(y)
relvis1= exp(-2*!pi*k^2*area[0])
relvis2= exp(-2*!pi*k^2*area[1])

phz1 = 2*!pi*(kx*x1[0]+ky*y1[0])
phz2 = 2*!pi*(kx*x1[1]+ky*y1[1])

i=complex(0,1)

vis1 = relvis1*flux[0]*exp(i*phz1) 
vis2 = relvis2*flux[1]*exp(i*phz2)
vis=vis1+vis2
amp=abs(Vis)
if keyword_set(plot) then begin
;   window,/free
   ti='TWO-SOURCE VISIBILITY AMPLITUDE FOR SC '+strcompress(fix(sc),/rem)
   
   plot,float(vis1),/xst,/yst,tit=ti,yra=[-1,1]*total(flux),psym=-6,symsiz=0.3
   oplot,imaginary(vis1),line=-2,psym=-6,symsiz=0.3
   oplot,float(vis2),line=-2
;   for j=0,8 do oplot,32*[j,j],[0.01,1]*total(flux)
 ;  legend,/right,/bottom,['Flux='+strcompress(flux[0],/rem)+strcompress(flux[1]),$
  ;                        'xpos='+strcompress(x[0],/rem)+strcompress(x[1]),$
   ;                       'ypos='+strcompress(y[0],/rem)+strcompress(y[1]),$
    ;                      'area='+strcompress(area[0],/rem)+strcompress(area[1])],/clear,textcolor=1
  
print,sc,correlate( float(vis1),imaginary(vis1))
print,sc,correlate( float(vis2),imaginary(vis2))
stop

endif

;stop
return,vis

end

area=!pi*[2,2]^2
flux=[200.,100.]
x=[-20,20]
y=[-20,20]
!p.multi=[0,3,3]
for sc=1,9 do begin
  vism=two_src_visibility1(flux,area,x,y,sc,/plot)
;  plot,vism,tit='SC='+strcompress(sc,/rem),yra=[-300,300],/xst,/yst,psym=-6,symsiz=0.3
;  oplot,imaginary(vism),line=2
;write_png,'2src_visF200-100W3-3.png',255b-tvrd()
endfor



end