[evlatests] 25, RCP, temporary 'weakness'

[Michael Rupen]

>    Antenna 25, in RCP only, on all four subbands, suffered an apparent
> loss in sensitivity by a factor of ~12% (in amplitude) for two hours (10
> -- 12 IAT).  The effect was not uniform for all sources -- some sources
> showed this during this period, others did not.  And the effect was not
> restricted to a subset of the five different sources -- they all showed
> it on some of the scans during that period, and they all showed it was
> absent on other scans during this same period ...  There was no phase
> effect.
>
>    No explanation is offered by me ...


1- Was this a loss in sensitivity or just a reduction in amplitude?

2- Did this show up in RL and LR as well as RR?  I assume this was the long,
   full-pol'n, C0555plus23 run.  Alas we have no auto-correlations for that
   run.

3- Was the effect constant throughout a scan?  I.e., if it's down by 12% for
   one integration in a scan, is it down by 12% for all of them?

Assuming this is a reduction in amplitude, with the bandpass just offset by
a single factor, and that it affected all RCP data, this has to be either
at the antenna or at the input to the Station Board.  A mechanism for an error
within the correlator seems difficult, but maybe I'm just not imaginative 
enough.  Lots of interesting oddities it seems...