[daip] DBCON

[Andy Biggs]

Hi there. I need some advice about the combination of VLA and MERLIN data 
that I'm currently attempting. Both datasets have multiple channels (for 
wide-field imaging) and in the past e.g. Muxlow et al. 2005, this has been 
done in the map plane. I'm attempting to do it in the uv plane, thus:

For the VLA dataset, for each IF, I UVCOP each channel into a separate 
dataset and then DBCON these back together. DBCON applies the appropriate 
scaling to the u, v and w's and I run the task with DOARRAY=-1 so that 
each channel is kept as a separate subarray. I then DBCON each IF together 
in the same way.

I repeat the same process for the 30 channels, single IF, of the MERLIN 
data.

In order to check that this process works I have mapped the resultant 
DBCON files and compared them to the original files and the results seem 
pretty much identical.

I'm now trying to DBCON the MERLIN and VLA single-channel datasets 
together. When I do this I'm not sure what to set FQTOL to. With it at its 
default (-1) DBCON complains that:

harpor> DBCON1: FQIDS HAVE NOT BEEN RESET AS THEY SHOULD DUE TO FQTOL
harpor> DBCON1: OR DUE TO THERE BEING NO FQ RANDOM PARAMETER

Maybe this is nothing to worry about, but I'd like to be sure.

By the way, in general, should this technique for combining multi-channel 
VLA and MERLIN data work okay?

Cheers,

Andy