[daip] SNPLT

[Eric Greisen]

Laura Chomiuk wrote:
> Hi Eric,
> 	I've noticed a slight oddity in SNPLT, i think.
> 
> Let's say I do a phase-only calibration on my phase calibrator (called
> PCAL), and generate a SN Table 1. Then i run clcal to
> apply this calibration only to PCAL itself
> 
> sour PCAL
> calsour PCAL
> snver 1
> inver 1
> gainver 1
> gainu 2
> go clcal
> 
> Then I do an A&P calibration and generate SN table 2, and want to
> supplement CL table 2 with this additional calibration. This time, i'd
> also like to apply this whole calibration to the science source too, so i
> do:
> 
> sour PCAL, SCIENCE
> calsour PCAL
> snver 2
> inver 2
> gainver 2
> gainu 3
> go clcal
> 
> When I look at CL table 3 in SNPLT, it looks like the SCIENCE target does
> not have any solutions on it. At first, i though this meant that because
> there were no solutions in CL table 2 for the SCIENCE target, there could
> be no solutions in CL table 3 for it either (as 3 builds on 2). But, if i
> look at the CL table in PRTAB, it does appear that there are entries in
> the CL table during the times when the science source is observed.
> 
> So, I think this is just an issue with SNPLT? It does indeed appear that my
> science data are getting calibrated, even though SNPLT implies that they
> are not.
> 
> Thanks!
> 	Laura

I do not think this is SNPLT unless you are using it oddly (e.g. 
specifying SOURCES to include only PCAL).  It would seem that you are 
calibrating PCAL in phase in CL 2 - then using CL 2 to get A & P from 
PCAL which would have a full Amp but only tiny or 0 phase in SN table 2 
and you are using that 0 phase to apply to SCIENCE ignoring the big 
phases found previously.  CLCAL is a tricky program and one has to be 
very careful using it.  In PRTAB you need to look at real and imaginary 
and weight and the former cannot be INDE and the latter cannot be <= 0 
if there will be real cals to apply.

I don't know what else to say without looking at your tables in detail.
I find CLCAL very confusing and have not looked at it lately.

Sorry for the delay answering - I have been away on vacation.

Eric Greisen