AIPS HELP file for VLBACALA in 31DEC22
As of Thu Jun 8 16:04:08 2023
VLBACALA: Applies a-priori amplitude and sampling corrections
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VLBACALA is obsolete, please see explain file
Use: ! VLBACALC is obsolete, there is a new amplitude !
! calibration scheme that is prefered. See explain !
! file for details. !
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
INCLASS....The class of the file to be corrected. Wildcard characters are
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.
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VLBACALC is obsolete, there is a new amplitude calibration scheme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,
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.