function gevloc_addpolar, gevloc

if not required_tags(gevloc,'xcen,ycen,date_obs') then begin 
   box_message,'Expect latest events location structures..'
   return,-1
endif


retval=gevloc
if not required_tags(gevloc,'fr,fphi') then begin 
   retval=add_tag(temporary(retval),0.,'FR')
   retval=add_tag(temporary(retval),0.,'FPHI')
endif

sr=get_rb0p(anytim(gevloc.date_obs,/int),/radius) ; solarR 

soho=strpos(gevloc.lfiles,'eit') ne -1 ;
sr=sr+((.01*sr*soho)) ; adjust SolarR for L1


locR=sqrt((gevloc.xcen^2.)+(gevloc.ycen^2.))
retval.FR=locR/sr  ; event location in  

return,retval
end