PRO cirplot,clat,clon,gcrad

;procedure to plot a circle on a lat/lon image
;IN: clat, clon : centre latitude and lungitude of image
;  : gcrad : radius of circle in radians
;nza is the nuber of circles to be plotted.
nza=1
hang=!DTOR*15.*(FINDGEN(nza)+1)
gcrad=!DTOR*gcrad

;figure plotted is actually a 37 sided polynomial
naz=37
az=FINDGEN(naz)*360./(naz-1)
hlon=FLTARR(naz,nza)
hlat=hlon

;loop present in case nza is GT 1
FOR i=0,naz-1 DO BEGIN
    ;change range and bearing to lat/lon
    rb2ll,clon,clat,gcrad,az(i),alon,alat
    hlon(i,*)=alon
    hlat(i,*)=alat
ENDFOR
PLOTS,hlon(*,3)-360.,hlat(*,3)
gcrad=!RADEG*gcrad
RETURN
END