pro centroid,array,column,row,ccentroid,rcentroid,dntotal,initialize,coldim,rowdim
;
;   finds the centroid of a point source image in array and
;   returns the integrated DN within a circle of radius 2 pixel
;  the variable initialize should be set to .true. the first
;  time this routine is called, and not set afterwards
;
;if initialize then begin
initialize = 1
z=size(array)
coldim=z(z(0)-1)
rowdim=z(z(0))
;end
;
; form sub-array around bright pixel
;
i1 = max([column-3,0])
i2 = min([column+3,coldim-1])
j1 = max([row-3,0])
j2 = min([row+3,rowdim-1])
datarr=double(array(i1:i2,j1:j2))>1.
;surface,datarr
dntotal=total(datarr)
xarr=datarr
yarr=datarr
idim = i2-i1+1
jdim = j2-j1+1
xs = double(indgen(idim)+i1)
ys = double(indgen(jdim)+j1)
for j = 0,jdim-1 do xarr(0:idim-1,j) = xs
for i = 0,idim-1 do yarr(i,0:jdim-1) = ys
ccentroid = total(datarr*xarr)/dntotal
rcentroid = total(datarr*yarr)/dntotal
;if ccentroid lt 0. or rcentroid lt 0. then stop
return
end