[daip] AIPS troubleshooting, multiple ASDM configurations

[Eric Greisen]

On 10/22/2015 03:10 PM, Wen-fai Fong wrote:
> Dear Eric,
>
> I'm working with a VLA continuum data set in AIPS. BDFLIST shows that I
> have 2 configurations (0 and 1) which are virtually identical in
> frequency, number of spectral windows, etc. Configuration 0 refers to
> the flux calibrator, while configuration 1 refers to the phase
> calibrator and my source, which comes right after the observation of the
> flux cal. Ideally I would be able to combine the two and preserve the
> time stamps and all scans.
>
> I understand that I can't load multiple configurations in a single run
> of BDF2AIPS, so I've run it twice to load each configuration separately.
> Then I used DBCON to combine the two data sets. I noticed when running
> listr that the scans go from ~1 min long to ~7 min long, so it seems to
> want to preserve the number of scans.
>
> Is this the best way to go about this? And is there a way to preserve
> the scan length of ~1 min?
>
> Thanks,
>
> Wen-fai Fong

If DBCON is willing to combine the 2 data sets then I find it odd that
they were 2 configurations to begin with.  It should be fine to combine 
the 2 in that case.

DBCON, unlike many AIPS tasks, goes to some work to ignore the input 
index tables.  It then makes the "natural" scans found in your data.  Is 
there some reason to have 7 consecutive 1 minute scans?  I can not think 
of a reason in AIPS calibration to require that.  You can force the CL 
table interval to be short (we have users that use 1 sec CL table 
intervals for special reasons!).  I would worry that scheduling such 
short scans would incur overhead during the observing and might well 
have a few bad samples in each scan at the start.

It would be rather some work to get DBCON to manage NX tables to 
preserve the scan structure and it might not even be possible in some 
cases but it might work in others.  I will consider this for the future 
but it will not happen immediately.

Eric Greisen