Antenna pointing

Currently the mean blind pointing accuracy of the antennas is ~40” at night and 50” during the day, with a few outliers. The pointing performance is monitored and an updated pointing solution model for each antenna/band is fitted at a monthly interval. Referenced pointing has not yet been implemented as a standard procedure. If your field has relatively bright sources near or past the half-power point, you will likely need to apply direction dependent calibration procedures.

If looking at older data, please bear in mind that some antennas were found retrospectively to have unstable or steadily deteriorating pointing. Antenna pointing errors will manifest as amplitude errors, and need to be addressed using direction-dependent calibration. Severe antenna pointing errors (~0.5 degrees or more) will manifest as a steep slope in the bandpass solutions, lower gain and a higher than normal delay. These antennas will need to be flagged.

An example of the effect of high pointing offset on the antenna bandpass response. In this case M032 and M057 show an abnormal response and were subsequently found to have pointing offsets of ~30 arcmin.