;&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
pro etc_rc,rmag,wcen=wcen,res=res,snr=snr,time=time
;
ress=[370,400,750,1000,1350,1500,2100,2950]   ;available R
dw=[17.2,16.4,8.6,6.5,4.8,4.3,3.1,2.2]
qe=[.13,.18,.15,.17,.15,.15,.13,.12]
if n_elements(rmag) eq 0 then rmag=10
if n_elements(wcen) eq 0 then wcen=6700.
if n_elements(res) eq 0 then res=2100
ii=fix(xindex(ress,res)+0.5)
;
gain=0.96 & rn=6.5
;
f0=2.25e-9
area=75.^2*!pi
hcl=6.62*2.99792E-9/wcen
;
cps=area*f0/hcl*dw(ii)/3.*qe(ii)*2.512^(-rmag)
;
print,' Count rate = ',cps,' counts per second
;
if keyword_set(time) then begin
   time=time>1.
   cts=cps*time*gain
   noise=sqrt(cts)+rn
   sn=cts/noise
   print,' S/N= ',sn,' in ',time,' sec'
   endif
if keyword_set(snr) then begin
   snr=snr>3.
   t=snr*snr/cps/gain
   print,' Approximately ',t,' sec needed to obtain SN=',snr
   endif
;
if keyword_set(stp) then stop,'ETC_RC>>>'
return
end