[daip] modification to WTMOD

[Andy Biggs]

Hi there. I was wondering whether it would be possible to modify WTMOD. I 
would like to give it a number *per antenna* which could then be used as a 
multiplier for the existing weights to that antenna. At the moment the 
multiplier is single valued i.e. the weights on each baseline are scaled 
identically. Perhaps the ANTWT array could be viewed as containing either 
absolute weights or scaling factors, which being dependent on some other 
parameter.

At the minute, the standard MERLIN data reduction path makes no attempt to 
calibrate the relative antenna weights based on initial gross amplitude 
corrections from a flux calibrator. Instead, WTMOD is used to insert 
nominal values for each antenna's weight, after calibration (i.e. just 
before mapping). This however loses weight info which has been gleaned 
during amplitude calibration using the phase reference source; data at low 
elevation, for example. If instead the nominal weights could be used as 
multipliers, then this useful information could be retained.

Cheers,

Andy