... The model for each receiver differs from the sband narrow model by an offset in azimuth (great circle) and zenith angle .These offsets are computed by tracking the above source (or sources) rise to set and computing the difference in pointing errors between sband narrow and the new receiver. ... The table below has the rms pointing error for each receiver on CTA21 and the rms of the difference in pointing error between the receiver and sband narrow: . receiver . Rms azErr . Rms zaErr . ...