Efficiencies from Moon measurements

At irregular intervals measurements of the Moon have been made with different receivers. They can be used to derive the Moon Efficiency of the telescope (by some called eta_fss) using values for the Moon temperature at the time of observation following Mangum (1993, PASP 105, 117). The time (Days) since New Moon was calculated using values found here.

Below are listed measurements obtained with the DAS using receivers RxA2 (DSB), RxA3i (DSB), RxB3i (DSB), RxB3 (SSB or DSB), RxC2 (DSB) and RxW (SSB). Some measurements close to New Moon gave efficiencies larger than 1.0 for unclear reasons. The adopted temperatures near New Moon are consistent with those measured by Fedoseev and Chernyshev (1997, Astronomy Reports 42, 105). Omitting these data, the average efficiencies are equal within the uncertainties (given is the mean error, not standard deviation) for all receivers except RxB3:
0.697 +/- 0.013 (RxA2),
0.715 +/- 0.004 (RxA3i),
0.694 +/- 0.006 (RxB3i),
0.710 +/- 0.037 (RxC2),
0.696 +/- 0.022 (RxW) (0.730 +/- 0.016 C-band; 0.650 +/- 0.032 D-band).
For RxB3 the efficiency is slightly higher: 0.758 +/- 0.020 (those from SSB measurements (0.756 +/- 0.023) and from early DSB measurements (0.764 +/- 0.045) agree, but there is a large range in values, possibly due to atmospheric conditions).

RxA2

RxA3i

RxB3i

RxB3

RxC2

RxW

Jan Wouterloot