AIPS HELP file for VLBACALA in 31DEC25

As of Wed Mar 26 18:53:56 2025

INPUTS

INNAME                             Input file name
INCLASS                            Input file class
INSEQ                              Input file sequence number
INDISK                             Disk number for input file
FREQID                             Frequency ID to correct
                                     0 => 1
SUBARRAY                           Subarray to correct. 0=>ALL
DOFIT                              Fit for opacity correction
BADDISK                            Disks to avoid for scratch

          VLBACALA is defined in the VLBAUTIL run file.
          VLBACALA is obsolete, use VLBAAMP instead

HELP SECTION

VLBACALA
Type: Procedure
Use:  !   VLBACALA is obsolete, there is a new amplitude    !
      !   calibration scheme that is prefered.  See explain !
      !   file for details.  Use VLBAAMP instead            !

      VLBACALA is a procedure that applies a-priori amplitude
      corrections and digital sampling corrections to VLBA data. These
      corrections are added to the corrections in the highest numbered
      CL table.

      VLBACALA assumes that you already have GC and TY tables and that
      you have at least one CL table.

      Type RUN VLBAUTIL to define the VLBACALA procedure.

  INNAME.....The name of the file to be corrected. Wildcard characters
             are allowed.
  INCLASS....The class of the file to be corrected. Wildcard characters
             are allowed.
  INSEQ......The sequence number of the file to be corrected. Zero
             defaults to the highest sequence number of a file matching
             INNAME, INCLASS, and INDISK.
  INDISK.....The disk drive number of the file to be corrected. Zero
             defaults to any disk.
  FREQID.....The frequency ID to correct. Zero defaults to frequency
             ID 1.
  SUBARRAY...The subarray to correct. Zero defaults to doing all.
  DOFIT......Do opacity correction in APCAL.  This is recommended
             for high frequency experiments (freq >= 15~GHz) if the
             accuray of the source flux is important.
  BADDISK....A list of disks on which scratch files are not to
             be placed.  This will not affect the output file.

EXPLAIN SECTION

VLBACALA:           Procedure to apply a-priori amplitude corrections
Documentor:         Chris Flatters
Related Programs:   VLBAUTIL, ACCOR, APCAL, SNSMO, CLCAL

VLBACALC is obsolete, there is a new amplitude calibration scheme
that is prefered.  This redesign of the amplitude calibration path is
based on VLBA Scientific Memo #37 (Craig Walker).  The new recommended
steps for amplitude calibration are:
  1) Do preliminary calibration steps that are necessary (e.g., VLBAFIX,
      VLBAEOPS, VLBATECR...).
  2) VLBACCOR -- digital sampling corrections
  3) VLBAMPCL (or VLBAPCOR) -- remove instrumental delay
  4) VLBABPSS -- do bandpass and correct auto-correlations
  5) VLBAAMP -- a priori amplitude calibration
  6) Continue with calibration.

VLBACALA determines amplitude corrections for digital sampling effects
and a-priori amplitude corrections from the gain curves and system
temperature measurements, removes bad points, and applies these
corrections to the highest numbered calibration (CL) table attached to
the input file.  Note that interpolation type 'SELF' is used for the
a-priori amplitude calibration, to avoid interpolating between sources
at different elevations, among other things.

You should run VLBACALA after correcting the polarization labels (if
necessary) and loading any gain curves or system temperature data for
non-VLBA antennas using ANTAB.