[daip] IMAGR average spectral index

[Eric Greisen]

Andy Biggs writes:
 > Hi there. I'm probably just being paranoid, but I'd like to check that the 
 > IMAGR average spectral index correction is believed to work. When I run it 
 > with this option enabled there are no obvious signs that any correction is 
 > being applied. In contrast, the primary beam correction reports that CC 
 > components are being scaled. I'm running an up-to-date version of aips.
 > 

If you do the average spectral index option, the data are scaled as
they are read to the work file.  Nothing else is required and I
suspect that this happens rather quietly.  The spectral index image
options are expensize as is the primary beam option because in those
cases one must modify the CC model and so subtract only a channel at a
time (or group of channels).

Eric Greisen