[daip] APCAL OPACOR error {External}

[Lai Kah Chun]

Hi,
I'm Lai, master research student from University Malaya, calibrating data
using MOJAVE raw data BG173b. I'm using AIPS version 31DEC20. The OPACOR
keep running into this problem:
APCAL1 17:23:17 Task APCAL  (release of 31DEC20) begins
APCAL1 17:23:17 TXTWX: Weather data read from WX table   1
APCAL1 17:23:17 Writing SN table   2 for subarray  1
APCAL1 17:23:17 BR       RCP 0/19h 1m Trec (K):    47.36 Zen. opac.: -0.011
APCAL1 17:23:17 OPACOR: ERROR:BR  RCP Tau0 (K),  -0.01, unreasonable value.
APCAL1 17:23:17       --This is probably due to bad data in TY table,
APCAL1 17:23:17         do some editing and try again.
APCAL1 17:23:17 Purports to die of UNNATURAL causes
APCAL1 17:23:17 localhos 31DEC20 TST: Cpu=      0.0  Real=      0  IO=
    3

Tsys looks fine and it should get a fit. This problem remain when I try
with another set of data BL137. For BL137 I then use opcode 'GRID' and
manage to get it run without error, but return Zen. opac=0 for every
antenna. For BG173b none of the opcode works, 'GRID,GRDR,OPAC,OPCR,LESQ',
all failed with the same negative zen. opac problem. I also tried with
31DEC19, but the same happens.
I saw a thread in daip that is posted by Lister, M., "problems with APCAL',
where his seems to describe the same problem as mine. But the thread ended
abruptly. I guess that would be helpful for me.
Below is my adverbs:

AIPS 1: APCAL     Task to generate an amplitude calibration SN table
AIPS 1: Adverbs     Values                 Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: INNAME     '070927'                Input UV file name (name)
AIPS 1: INCLASS    '7GHZ'                  Input UV file name (class)
AIPS 1: INSEQ         1                    Input UV file name (seq. #)
AIPS 1: INDISK        1                    Input UV file disk unit #
AIPS 1:
AIPS 1: ANTENNAS   *all 0                  Antennas to calibrate
AIPS 1: SUBARRAY      0                    Subarray 0 -> all
AIPS 1: STOKES     ' '                     Stokes type ('R','L',' ')
AIPS 1: BIF           1                    Start IF number
AIPS 1: EIF           4                    End IF number
AIPS 1: FREQID       -1                    Freq. ID to calibrate
AIPS 1: SOURCES    *all ' '                Sources to calibrate
AIPS 1: TIMERANG   *all 0                  Time range to calibrate
AIPS 1:
AIPS 1: TYVER         1                    TY table version number.
AIPS 1: GCVER         1                    GC table version number.
AIPS 1: SNVER         2                    Output SN table version.
AIPS 1:                                      0 -> highest unique
AIPS 1:                                      appends to existing file
AIPS 1: OPCODE     'LESQ'                  Opacity correction opcode:
AIPS 1:                                    '    ' -> no opacity corr.
AIPS 1:                                    'GRID','GRDR','OPAC','OPCR',
AIPS 1:                                      'LESQ' -> fit for opacity
AIPS 1:                                    'PLOT' plot input fit
AIPS 1: APARM      *all 0                  Calibration parameters:
AIPS 1:                                    (1) -> B factor (def. 1.0)
AIPS 1:                                    Opacity parameters:
AIPS 1:                                    (2) -> ZA limit (deg)
AIPS 1:                                    (3) >=0  use spillover
AIPS 1:                                             correction
AIPS 1:                                    (4) > 0  use all FQ in
AIPS 1:                                             opac. soln.
AIPS 1:                                    (5) Limit to sec(z) plotted
AIPS 1:                                    (6) > 0 => normalize Tsys
AIPS 1:                                        by average Tsys
AIPS 1:                                    (7) Use IF AP(7) for
AIPS 1:                                        normalization instead
AIPS 1: SOLINT        0                    Solution interval (min)
AIPS 1:                                       0 -> use all data
AIPS 1: INVERS        1                    WX table version number.
AIPS 1:                                       0 -> use text file
AIPS 1: CALIN      *all ' '                Text file with weather info.
AIPS 1:                                       Must be ' ' if using WX
AIPS 1:                                       table (INVERS).
AIPS 1: TRECVR     *all 0                    Receiver temperatures (K);
AIPS 1:                                       in (R,L) pairs.
AIPS 1: TAU0       *all 0                  Zenith opacities (per ant.)
AIPS 1: DOFIT         1           1        Fit type (per ant.)
AIPS 1:               1           1          -1 -> no opacity correction
AIPS 1:               1           1           0 -> apply TRECVR only
AIPS 1:               1           1           1 -> solve for Trec using
AIPS 1:               1           1                fitting method spec.
AIPS 1:               1           1                in OPCODE; then apply
AIPS 1:               1           1           1           1
AIPS 1:               1           1           1           1
AIPS 1:               1           1           1           1
AIPS 1:               1           1           1           1
AIPS 1:               1           1
AIPS 1: PRTLEV        1                    Print level
AIPS 1: DOTV          1                    TV selection (<0 -> PL file)
AIPS 1: LTYPE         3                    Plot labeling
AIPS 1: GRCHAN        0                    TV Graphics channel to use


Regards,
Lai
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