Setup

The reference antenna is a 1.2m satellite dish located on the control building, about 200 m from the main antenna. Both antennas have good room temperature receivers (Tsys $\sim$ 80 K). Both are equipped with quality low phase noise down converters. The reference antenna has an IF of 995.004 MHz, suitable for the VLBA terminal.

The 100m signal is presented to the mk4 terminal at a frequency of 150 MHz.

The two IFs were offset by 120 hz in order to have a useful fringe rate at the correlator.

In both cases the signal was bandpass filtered - 10 MHz at the receivers, 2.5 MHz in the control room (for data archiving) and 1 MHz at the VLB terminals.

Dynamic range is a serious issue in this experiment - the signal strength is many times Tsys when the 100m antenna points directly at the satellite. We therefore recorded a second, low sensitivity channel from the 100m; this had an effective Tsys of $\sim$ 28000 K. We use the high sensitivity channel for all the beam pattern, except for about a dozen points around the boresight, for which we use the low sensitivity data.

For calibration we use four panels with offsets $\pm$3 mm (ring 7, 9 and 13).