[evlatests] Tcal accuries at P-band

[Vivek Dhawan]

Hi Rick,

I'm sure you appreciate this, but its worth reiterating, since we
assume in TYAPL that all antennas have the same gain, (Jy/K), the
CALIB gains are measures of (G/T) not T alone.

I would not be surprised if the gains spread by many%, so I would not
change the Tcal values without an independent measure of the G's via
say an on/off measurement on a strong known source. Even if the absolute
flux is uncertain, the relative gains can be measured.

And if we are doing the Tcal fudge at P band, why not at all the other
bands as I have lobbied for before?


On Tue, September 2, 2014 18:06, Rick Perley wrote:

|      Here I report on the accuracy of the Tcal values.
|

|      The not-so-quite good news is that there is a large scatter. Below
| are the CALIB gains needed to bring the data into alignment with the
| correct flux densities.  Presuming the utilized efficiencies are
| correct, and are the same for every antenna, the error is in the values
| of the Tcals.  The needed correction to the Tcal values is the square of
| the gain factor listed.  Hence, if the gain factor is 1.1, then the Tcal
| value should be increased by 1.21.
|