The multibeam receiver was designed to have high performance for 21cm line work. This was achieved by compromising performance in other areas such as frequency range and polarisation purity. The following table lists the receiver specifications. Temperatures are measured at a frequency of 1394.5 MHz over a bandwidth of 64 MHz. The above diagram shows the configuration of the feed system as projected onto the sky when the feed angle is 0 o and the telescope is observing on the northern meridian.
North is to the top, east to the left.
When the feed angle is 0 o , beam 3 is closest to the lift leg which lies on the downhill side of the prime focus cabin. Normally, the multibeam receiver is used to map extended areas. Typically the feed angle is set to 15 o to the scanning angle. The scanning rate is usually around 1 o min -1 . This is to avoid problems with the changing bandpass as the receiver rotates.