[daip] CALIB recalibrating weights in output data file

[Eric Greisen]

Modhurita Mitra wrote:
> Hi,
> 
> I ran CALIB on a single-source data file to produce a calibrated output 
> data file. For one antenna I found that the input and output visibility 
> weights were very different (the weights increased in the output file). 
> I am trying to determine why this happened. How does CALIB calculate the 
> new weights for the output file?

When there are amplitude changes, it is assumed that the scaling error 
was due to incorrect Tsys calibration which applies to the weights as 
well as to the visibilities.  If the vis amplitude is multiplied by X 
the weights are divided by X*X.

This is not done to EVLA data initially since the weights are simply 
integration counts.  After TYAPL or REWAY, when weights have become real 
weights, the scaling is done.

Eric Greisen