[daip] weirdness with IF2

[Stan Kurtz]

Dear AIPS Wizards:

This problem probably isn't worth you spending much time on, but if I
could get 60 seconds of thoughts/ideas/suggestions, I'd appreciate it!

I have a student doing some work in Mexico City and the computer staff
there installed 31DEC04 on a linux box the last week of October.
They've done AIPS installations before, and that I'm aware of, there
were no problems with this installation.

I had the student down-load AF386 from the data archive, and she reported
problems with IF2, namely thousands of Jy of flux.  I looked at the same
data at the AOC several weeks ago (with 31DEC04) and both IFs were fine.
I downloaded the data from the archive to my machine in Morelia (31DEC02)
and both IFs look fine.  I copied the same data that worked with 31DEC02
to the Mexico City machine, re-FILLed it, exactly as I'd done before,
and sure enough, with that version of AIPS, IF2 has Kilo-Jy of flux.
If I do a PRTUV everything looks fine.  But UVPLT and TVFLG both see
Kilo-Jy fluxes on many (though not all) baselines.  I've attached uvplts
of both IFs.  There's some interesting structure in the IF2 plot that
might provide some hint of what's going on.  FILLM inputs were:

AIPS 1: FILLM     Task to read a VLA archive tape
AIPS 1: Adverbs     Values                 Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: INTAPE        1                    Tape drive number
AIPS 1: INFILE     'FITS:CRIS/AF386_                                '
AIPS 1:                                    Non-blank: disk file name
AIPS 1: NFILES        0                    Number of files to advance
AIPS 1:                                    Also applies to ON-LINE!
AIPS 1: BAND       '    '                  Freq. band (4,P,L,C,X,U,K,Q)
AIPS 1: QUAL         -1                    Source qualifier -1=>all
AIPS 1: CALCODE    '    '                  Calibrator code
AIPS 1: VLAOBS     '      '                VLA obs. pgm. name ('AZ99')
AIPS 1: VLAMODE    '  '                    VLA obs. mode ('  '=any)
AIPS 1: REFDATE    '        '              Reference date. 'yyyymmdd'
AIPS 1: TIMERANG   *all 0                  Timerange selected
AIPS 1: BCHAN         1                    First spectral channel
AIPS 1: ECHAN         0                    Highest spectral channel
AIPS 1: OUTNAME    'AF386       '          Output UV file name (name)
AIPS 1: OUTSEQ        0                    Output UV file name (seq. #)
AIPS 1: OUTDISK       2                    Output UV file disk unit #.
AIPS 1: DOUVCOMP     -1                    1 (T) => compressed data
AIPS 1: DOALL         1                    1 (T) => write all data.
AIPS 1: DOCONCAT     -1                    1 (T) => append data to old
AIPS 1:                                    files
AIPS 1: NCOUNT       12                    Number of files to read
AIPS 1: DOWEIGHT      1                    Use nominal sensitivity to
AIPS 1:                                    scale weights?
AIPS 1:                                    = 10, use Memo 108 weights
AIPS 1: DOACOR       -1                    Load autocorrelation data?
AIPS 1: CPARM         0           0        User options.
AIPS 1:               0           0        1 => Avg. time (seconds)
AIPS 1:               0           0        2 => bitmap    (see help)
AIPS 1:               0           0.5           = 16 for planets & Sun
AIPS 1:               0           0        3 => Max. OK IF status
AIPS 1:                                         <=3 => 3
AIPS 1:                                    4 => Control dropping of
AIPS 1:                                         shadowed data
AIPS 1:                                         < 0 => no shadow check
AIPS 1:                                         0 => 25 m limit
AIPS 1:                                         > 0 => Shadow limit is
AIPS 1:                                               CPARM(4) in meters
AIPS 1:                                    5 = channel code (see HELP)
AIPS 1:                                    6 => Subarray number-see HELP
AIPS 1:                                    7 => FQ entry tolerance (kHz)
AIPS 1:                                         (see HELP)
AIPS 1:                                    8 => CL table time incr. min
AIPS 1:                                    9 => TY table time incr. min
AIPS 1:                                    10=> Calibrator avg. time
AIPS 1: DPARM      *all 0                  Selection by Frequency
AIPS 1:                                    1+2 => A Frequency (Hz)
AIPS 1:                                    3+4 => B Frequency (Hz)
AIPS 1:                                    5+6 => C Frequency (Hz)
AIPS 1:                                    7+8 => D Frequency (Hz)
AIPS 1:                                    9 => tolerance for A&C
AIPS 1:                                    10 => tolerance for B&D
AIPS 1: BPARM      *all 0                  Opacity and Gain curve
AIPS 1:                                    control (see help)
AIPS 1: IN2FILE    '                                                '
AIPS 1:                                    Antenna gains file

Both the CL and TY tables have about the same entries for both IFs.

In the worst-case scenario I can always have the student come here to
Morelia to reduce the data, so it's not worth you doing a lot of head-
scratching.  But she would get a full month's head-start if she could
reduce the data in Mexico City.  So if you have any ideas/suggestions
for what I might look for, I'd appreciate hearing them!

Thanks very much, and best regards,
Stan
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