AIPS HELP file for VLBAMPCL in 31DEC25
As of Wed Mar 26 14:41:06 2025
VLBAMPCL: Procedure to manually correct instrumental phases
INPUTS
You must type RUN VLBAUTIL
to see all the inputs to
this procedure.
INNAME Input UV file name (name)
INCLASS Input UV file name (class)
INSEQ 0.0 9999.0 Input UV file name (seq. #)
INDISK 0.0 9.0 Input UV file disk unit #
TIMERANG Time range of a calibrator
1-4 = start day,hr,min,sec
5-8 = end day,hr,min,sec
MUST BE SPECIFIED
BCHAN 0.0 2048.0 Lowest channel number 0=>all
ECHAN 0.0 2048.0 Highest channel number
REFANT 0.0 20.0 Ref. antenna, 0=>the first
SUBARRAY 0.0 9999.0 Subarray; 0 => all.
CALSOUR Calibrator source name;
blank => any
GAINUSE CL table to use; 0=>highest
ADVERBS IF 2 SCANS MUST BE
USED TO CORRECT ALL ANTENNAS:
DOBAND -1.0 10.0 If >0 apply bandpass cal.
Method used depends on value
of DOBAND (see HELP file).
OPCODE 'CALP' if you are using 2
scans, otherwise ''
TIME2 Time range of a calibrator
1-4 = start day,hr,min,sec
5-8 = end day,hr,min,sec
SOURCES Calibrator source name for
TIME2 scan; blank => any
ANTENNAS antennas for which manual
phase corrections should be
obtained for the scan in
TIME2 (i.e. that cannot be
corrected with TIMERANG).
CHINC 1.0 Channel increment in FRING
< 0 -> find from data
HELP SECTION
VLBAMPCL
Type: Procedure
Use: VLBAMPCL is a procedure that creates a CL table which
corrects the instrumental phases and delays using
FRING. It will run FRING twice if there are no
scans that have good fringes on all antenna. This
should be run after VLBACALA (or VLBAPANG for
polarization experiments) but before VLBAFRNG/VLBAKRNG.
Type RUN VLBAUTIL to make the VLBAMPCL procedure
available.
Adverbs:
INNAME.....Input UV file name (name). Standard defaults.
INCLASS....Input UV file name (class). Standard defaults.
INSEQ......Input UV file name (seq. #). 0 => highest.
INDISK.....Disk drive # of input UV file. 0 => any.
TIMERANG...Time range of the calibrator to be used. In order:
Start day, hour, min. sec,
End day, hour, min. sec. Days relative to
reference date.
MUST BE SPECIFIED. Pick a scan on a calibrator where
ALL antennas are present and have strong fringes. If
there is no such scan, then use OPCODE, TIME2 and ANTENNAS
another scan and set of antennas.
BCHAN......First channel to use. 0=>all.
ECHAN......Highest channel to use. 0=>all higher than BCHAN
You may want to select BCHAN and ECHAN to leave out
edge channels if those are bad and will affect the
phase and delay solutions.
REFANT.....Reference antenna, 0 => the first in the antenna list
Set to a stable antenna that is preferably in the entire
experiment
SUBARRAY...The subarray to use. 0 => all
CALSOUR....Calibrator source name for scan in TIMERANG; blank => any.
GAINUSE....Number of CL table with all calibration up to this point.
0 => highest
DOBAND.....If there is a BP table, then correct the data for the
shape of the antenna bandpasses using the BP table.
Default = 1. The correction has five modes:
(a) if DOBAND=1 all entries for an antenna in the table
are averaged together before correcting the data.
(b) if DOBAND=2 the entry nearest in time (including
solution weights) is used to correct the data.
(c) if DOBAND=3 the table entries are interpolated in
time (using solution weights) and the data are then
corrected.
(d) if DOBAND=4 the entry nearest in time (ignoring
solution weights) is used to correct the data.
(e) if DOBAND=5 the table entries are interpolated in
time (ignoring solution weights) and the data are then
corrected.
OPCODE.....OPCODE in CLCAL; use the default if only one scan is
needed to correct all the antennas. If OPCODE is set
to 'CALP' and ANTENNAS and TIME2 are set then
instrumental phase correction will be found for a
second set of antennas (listed in ANTENNAS) for
another scan (specified by TIME2). If OPCODE='CALP'
but ANTENNAS and TIME2 are not set then only the
phase corrections that are corrected by the scan
specified in TIMERANG will be corrected. See EXPLAIN
file for a detailed explanation of how to deal with
antennas which are not corrected after VLBAMPCL.
TIME2......Time range of the calibrator to be used for second scan.
In order: Start day, hour, min, sec, End day, hour, min,
sec. Days relative to reference date.
MUST BE SPECIFIED IF OPCODE AND ANTENNAS ARE SPECIFIED.
Pick a scan on a calibrator where antennas listed in
ANTENNAS have strong fringes.
SOURCES....Calibrator source name for scan in TIME2; blank => any.
ANTENNAS...Antennas that will not be corrected with the scan
specified in TIMERANG but will be corrected by the
scan specified in TIME2. OPCODE must be set to
'CALP' for this option. 0=> do not find manual phase
correction for a second scan. MUST BE SPECIFIED IF
TIME2 IS SPECIFIED.
CHINC......< 0 -> adverb for FRING
set CHINC to 0.5E6 / (FREQ increment). One is
used for all but narrow-band spectroscopy data.
Channel increment in fitting - note channels are averaged
BCHAN to BCHAN+CHINC-1, BCHAN+CHINC to BCHAN+2*CHINC-1,
etc. This reduces the memory requirements and is
suitable for delay errors that are not too large to cause
channel-to-channel loss of coherence.
EXPLAIN SECTION
VLBAMPCL: Procedure to correct the instrumental phases
using FRING. It can find corrections for
a second scan if there are no scans that contain
all antennas.
Documenter: Amy Mioduszewski
Related Programs: VLBAUTIL, CLCAL, FRING, VLBAPCOR
This procedure should be used if there are no good phase
cals (e.g. spectral line experiments), otherwise use
VLBAPCOR.
This should be done after sampler corrections (VLBACCOR) and
before the bandpass (VLBABPSS). After VLBAMPCL is run it is
ESSENTIAL to check the solutions in POSSM setting GAINUSE to
the CL table output by VLBAMPCL.
VLBAMPCL assumes:
1. there is only one FREQID
2. that all IFs should be calibrated
6. that the highest FG table is the one that should be applied
Steps in VLBAMPCL:
1. Runs FRING, TIMERANG, CALSOUR, GAINUSE and REFANT as
specified; DOCAL=2, APARM(1)=2 and DPARM=1 0 0 0 0 0 0 1.
2. Runs CLCAL, with input OPCODE; ANTENNAS=0; INTERPOL='';
SNVER= SN table out of FRING; GAINVER = input GAINUSE;
and GAINUSE= highest CL table +1. Output should be highest
CL table.
*3. Runs FRING, using the GAINUSE used in CLCAL in step 2.
ANTENNAS=ANTENNAS, REFANT, rest the same as in step 1.
If FRING reports any "failed solutions" you MUST find
another scan and run again, after you have deleted the SN
and CL tables that VLBAPCOR has created. Unless there is a
good reason for failed solutions, such as an entire IF has
been flagged for a certain antenna.
*4. Runs CLCAL with ANTENNAS equal to the input ANTENNAS
GAINVER equal to input GAINUSE; SNVER equal to output
SN table from FRING; GAINUSE equal to the CL table
which is output in step 2; TIMERANG =0; and
CALSOUR = ''.
*NOTE: Steps 3 and 4 only take place if OPCODE='CALP' and
TIME2 and ANTENNAS <> 0.