[daip] "single source" CL table applied to multisource file

[Andrzej Marecki]

Dear DAIP(s),

Let me start with the famous: "this is something I always wanted to know
but was afraid to ask" or more specifically: there is something in AIPS
that - IMHO - should work another way but it works as it works and I don't 
understand why.

I decided to ask today after my student had made a mistake which,
because of that feature (or bug - you name it) of AIPS, resulted in
wrong results instead of... an error message.

In short the problem is the following: if a CL table contains the
information pertinent to *one* source how on earth could it calibrate
the UV data of some other sources in a multi-source file?

OK, let me explain it step by step what my student did.

1. She run FRING with CALSOUR='fringe-finder'. It produced an SN table
   with one point.
2. She applied that SN table to a CL table with OPTYPE='SELF' in CLCAL.
   The input CL table covered all the sources but the output CL table
   contained - and this was perfectly OK - the points related to the FF.
3. She, erroneously, specified *that* CL table number in GAINUSE parameter
   in a number of tasks to follow. And they worked fine for sources other
   than the FF!!! For example VPLOT with SOURCES='a_source_but_not_the_FF'
   produced apparently reasonable plots. Even worse: SPLIT (regardless
   of whether SOURCES was specified or not) split the data from that
   multisource file and the results apparently looked good but they were
   actually miscalibrated!

Andrzej

-- 
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Andrzej Marecki                | 
Torun Centre for Astronomy     |   e-mail: amr at astro.uni.torun.pl
N. Copernicus University       |   WWW:    http://www.astro.uni.torun.pl
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