[daip] forwarded message from Eric Greisen

[Eric Greisen]

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From: Eric Greisen <egreisen at nrao.edu>
To: "Matthew Sharp" <sharp at seek.uchicago.edu>
Subject: Re: [daip] AIPS help
Date: Fri, 1 Dec 2006 14:48:58 -0700

Matthew Sharp writes:

 >    I have many pleas: I'm trying to work through the calibration process
 > following chapter four of the AIPS cookbook, but I'm finding many points of
 > confusion.
 > 
 >    For the moment: I've managed to load my data, I found with LISTR that
 > several antennas had very large RMS/low amplitude, and so I used UVFLG to
 > flag these antennas in the proper time range.  Judging from the message
 > window, everything is working so far...
 > 
 >    Following blindly the cookbook, I arrive at 4.4.2, wherein EDITA is
 > explained as a tool for flagging on system temperature.  I start with
 > "default edita", and then enter the adverbs given in the cookbook.  on "GO",
 > my TV comes alive, with a panel for each antenna I've requested.  The
 > day/times listed at the bottom seem to bracket my entire dataset.
 > 
 >    Everything looks great, but each panel displays four horizontal lines, at
 > levels in the 25-40 K range.  ie, the Tsys reported is perfectly constant
 > over my 9 hour track.
 > 
 >    What could I have done wrong to break my Tsys like this?

Break?  Have you requested CROWDED TRUE?  If so, then you are
displaying 2 IFs and 2 polarizations all at once - something which the
labeling surrounding the plot will show you (or at least imply by
saying IF 0, polarization 0).  You can then select IF and/or
polarization and reduce the display to a single parameter at a time.
EDITA is often useful to flag data, but if you have already eliminated
the obvious things, it may not be useful at this point.  The CookBook
attempts to tell users about lots of things, not all of which are
appropriate at any one time.  Furthermore, especially in calibration,
there are disagreements on what is the best method and the CookBook
attempts to present some from all sides of the various arguments.

 > 
 >    Is this the kind of question the designated AIP is intended to address,
 > or have I in fact come to the wrong place?

We can certainly help you with details of the individual programs but
the aips group is not a replacement for a scientific advisor/teacher
which is the role of the faculty at U Chicago.
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