[daip] forwarded message from Eric Greisen

[Eric Greisen]

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From: Eric Greisen <egreisen at nrao.edu>
To: Daniel Lebach <dlebach at cfa.harvard.edu>
Subject: Re: [daip] CALIB failure (31DEC03 AIPS on DEC ALPHA) w/ basic settings
Date: Wed, 9 Jun 2004 15:10:40 -0600

Daniel Lebach writes:

 > > If you ask for only 2 antennas then you cannot get antenna-based
 > > solutions.  At least 4 antennas must be used.
 > > 
 > Is this a new feature?  I set APARM(1) = 2 (just as I always have).
 > I prefer to get solutions one baseline at a time to get phases that
 > include structure effects (note that I use no structure model).  If I
 > use more than 2 antennas then I am necessarily imposing closure
 > constraints, and I don't want that.  Note that the baseline-based
 > phases I get are exported out of AIPS (after the model phases are
 > added so that total phases are exported) for further analysis with
 > software designed to handle baseline data.  All I want from CALIB are
 > best-fit phase corrections to the phases in the input CL table
 > (SOLMODE 'P').  CALIB used to provide these for me just fine until
 > now.  Did CALIB change?  If so, can you provide me the source code
 > for the 31DEC02 version of CALIB?  I no longer have access to that.
 > (That old source code is useful only if I can embed it into
 > 31DEC03 AIPS.)

CALIB was always intended to do antenna based solutions, never to be
perverted in the fashion you are doing.  Nonetheless, the change to
prohibit your mode was made inadvertantly when fixing the code to
make a better default for small arrays.  I will change 31DEC04 back
but add a warning message to users who do not know what they are doing
- - unlike you most of them will not understand what a two antenna
solution actually does.

Eric Greisen
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