[daip] problem with AP94 data

[Jim Ulvestad]

Hi all,

This has nothing to do with VLA:PT.  FILLM was modified so that
it always looks for the locations of antennas 1 through 28,
and always lists PT as antenna 29.  This is true even if
the data were taken before PT ever existed--antenna number
29 is now hard-wired into FILLM.

The problem is one of errors that were made in creating the
archive--antennas tables are occasionally missing.
I found another case earlier this year, at around
15-August-1983, and reported it to the proper authorities.
However, barring someone trying to load the entire archive
to find such instances, we can only deal with them on
a case-by-case basis as they show up.

Below is a copy of a message I sent to the computer division
head in early January.  It might be useful for the data
analysts to start keeping a list of the data regions
where these errors occur.  (That list would at least
have two entries on it now.)

EMPHASIS--this is NOT an AIPS problem, but is a data
archive problem.  The only solution is to run FILLM
on several files around the offending one until a
valid antennas table is found.  Then one can delete
the original AN table from the AP94 data set, and
copy the correct AN table into AP94.

Suggested action for this or any other missing AN file.

(1) Analysts run FILLM on a few files around the one in
question and look for a valid AN table close to the 
missing one in time.  Make a note of the range of
files/times for which correct antenna information is 
missing.

(2) Analysts run TASAV on the data set with a valid AN
table to save all the tables to a  small file.

(3) Write the file output by TASAV to disk using FITTP.

(4) Make the disk file available to the astronomer via
anonymous ftp.

(5) Astronomer loads the disk file into AIPS using FITLD.

(6) Astronomer deletes the faulty AN table from his/her
uv data set, then uses TACOP to copy the correct AN
table into that data set.

This all should work--it's what I had to do a few
months ago.

jim

>From - Wed Jan  2 14:26:29 2002
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Date: Wed, 02 Jan 2002 14:26:29 -0700
From: Jim Ulvestad <julvesta at aoc.nrao.edu>
Reply-To: julvesta at aoc.nrao.edu
Organization: National Radio Astronomy Observatory
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To: gvanmoor at aoc.nrao.edu
Subject: VLA archive antenna files
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Hi Gustaaf,

Based on my sleuthing, Files 32 through 36 (AF70) on
tape XH83014 have antennas files that say all the
antennas are "OUT" (at least that's the result from FILLM).
Others in that vicinity seem okay.

File 37, also AF70, seems to have a valid antenna file,
as does File 38.  Prior to AF70, File 30 and 31,
AS80, seems to have a valid antenna file as well.
And, this file has the same antenna locations as File 37.
So I conclude that it's just the 5 files in that immediate
area that are messed up.

jim
Martin Hardcastle wrote:
> 
> > Your problem can be related with adding PT antenna to VLA.
> > I see that output of PRTAN has all antenna name as VLA:OUT but
> > the 29th antenna name is VLA:VPT.
> 
> I did wonder about that...
> 
> > Now you can copy the AN table (by the task 'tacop') from your new A-array
> > observations.
> 
> But I need an AN table with the correct antenna positions for B-array
> in May 1985, or UVFIX still won't work. Right?
> 
> If this is a problem with this dataset alone then I thought the
> analysts might be able to find another observation close to it in time
> in the archive that I could copy the AN table from...
> 
> Martin
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