AIPS HELP file for CLINV in 31DEC25

As of Mon Dec 9 12:56:36 2024

INPUTS

INNAME                             Input uv data name (name)
INCLASS                            Input uv data name (class)
INSEQ             0.0     9999.0   Input uv data name (seq. #)
INDISK            0.0        9.0   Input uv data disk unit #
INEXT                              Input table extension type
INVERS                             Input table file version no.
OUTNAME                            Output uv data name (name)
OUTCLASS                           Output uv data name (class)
OUTSEQ           -1.0     9999.0   Output uv data name (seq. #)
OUTDISK           0.0        9.0   Output uv data disk unit #.
OUTVERS                            Output table file version.
OPTYPE                             'PHAS' => invert phase only
                                   (output amplitude gain = 1)
                                   'AMPL' => invert amp. only
                                   (output phase = 0)
                                   otherwise completely invert
                                   the calibration

HELP SECTION

CLINV
Task:  CLINV inverts the calibration in an AIPS CL or SN extention
       table.  The specified output table should not exist before the
       execution of CLINV.
Adverbs:
  INNAME.....Input uv data set name (name).       Standard defaults.
  INCLASS....Input uv data set name (class).      Standard defaults.
  INSEQ......Input uv data set name (seq. #).     0 => 1.
  INDISK.....Disk drive # of input uv data set.   0 => any.
  INEXT......Extention table type (e.g. 'CL') ' ' => 'SN'
  INVERS.....Version number of table to copy, 0=>highest no.
  OUTNAME....Output uv data set name (name).      Standard defaults.
  OUTCLASS...Output uv data set name (class).     Standard defaults.
  OUTSEQ.....Output uv data set name (seq. #).    0 => highest unique.
  OUTDISK....Disk drive # of output uv data set.  0 => highest disk
             number with sufficient space.
  OUTVERS....Output version number, 0=> next higher.
  OPTYPE.....'PHAS' => invert phase only (output amplitude gain = 1)
             'AMPL' => invert amplitude only (output phase = 0)
             otherwise completely invert the calibration

EXPLAIN SECTION

CLINV
Task:  Calibration inversion

IF an AIPS CL or SN table has been applied to a data set and one wants
to undo the calibration (or the phase or amplitude part of the
calibration), one may use CLINV to produce an inverse table which may
then be applied to the data with SPLIT.  The example that caused this
task to be written is a field with a strong source at the half-power
point of the beam.  Pointing errors make calibration found with this
strong source inaccurate for sources near the center of the field, but
one has to self-cal on the strong source in order to remove it.
Therefore:

      1. Calibrate in the normal way and SPLIT
      2. Self-calibrate with a strong source in/near the field
      3. Run UVSUB to subtract that strong source
      4. Run CLINV on the self-calibration SN table attaching the
         inverse table to the output of UVSUB
      5. Undo the strong-source self-cal from the residual data by
         running SPLIT on the UVSUB/CLINV output file.