[evlatests] Troubles with amplitude scale

[Vivek Dhawan]

I think the scale factor for 3-level fringe rotation (~1.18) got left off,
and if applied lowers the calibrated flux, i.e. gets closer to the traditional
method using a source of known flux density.

Attached are 2 more emails from Rick and Brent that saw limited circulation.
Eric coded TYAPL in AIPS based on Rick's email, the 1.18 is not in there.

Rick Perley wrote:
>     The 'Herc A Demo Project' data from earlier this week is being 
> reduced.  Two problems are immediately apparent from X-band calibration:
>    
> 1) The implementation of the switched power system is intended to (and 
> should!) convert our raw correlation products into physical units, in 
> Janskys.  It's close, but there is an offset.  Vivek has reported 
> privately that 3C84 test data taken at C and K bands were being 
> overcorrected.  This is also the case at X-band, where I've used 3C286 
> to establish that most antennas are being overcorrected by a factor 
> between 25 and 30% (in power).  Nearly all antennas show the same factor 
> on all subbands and both polarizations.    An overcorrection can occur 
> from three different ways:

>     a) A mis-scaling, caused perhaps by an errant coefficient, or a 
> misunderstanding of the meaning of a monitor value

>     b) An antenna efficiency better than that assumed (I think we're 
> using 60% for X-band)

>     c) A Tcal which is actually lower than those in the tabulated values. 
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