AIPS HELP file for VLBAFRNG in 31DEC24
As of Wed Apr 24 6:10:18 2024
VLBAFRNG: Procedure to fringe fit and calibrate data
INPUTS
Input uv data.
INNAME UV file name (name)
INCLASS UV file name (class)
INSEQ 0.0 9999.0 UV file name (seq. #)
INDISK 0.0 9.0 UV file disk drive #
CALSOUR Source list to fringe fit
TIMERANG Time range to use.
BCHAN 0.0 2048.0 Lowest channel number 0=>all
FOR SPEC. LINE EXP. ONLY
ECHAN 0.0 2048.0 Highest channel number
FOR SPEC. LINE EXP. ONLY
GAINUSE CL table to apply.
REFANT Reference antenna
SUBARRAY 0.0 1000.0 Subarray, 0=>all
SEARCH 0.0 1000.0 Prioritized reference antenna
list - supplements REFANT
SOLINT Solution interval (min)
0 => 10 min
DPARM for strong sources, it is
only necessary to set
DPARM(4), DPARM(7) and for
spec line exp DPARM(8).
4=int. time (sec)
0 => min. found in data
7 >0 => don't rereference
phase; this should be 1
for polarization exp
8 > 0 => activate zero'ing
options
for rest see HELP VLBAFRNG
SOURCES Source list to calibrate: If
sources are listed they are
each calibrated with separate
runs of CLCAL
CHINC 1.0 Channel increment in FRING
< 0 -> find from data
INTERPOL Interpolation function:
'2PT','SIMP','AMBG','CUBE',
'SELF'
BADDISK 0.0 15.0 Disk no. not to use for
scratch files.
HELP SECTION
VLBAFRNG
Type: Procedure
Use: This procedure does antenna based fringe fitting using FRING
and then applies those corrections using CLCAL. For more
information on FRING and CLCAL see their respective HELP/EXPLAIN
files. If you are doing a phase reference experiment use
VLBAFRGP.
Type RUN VLBAUTIL to make the VLBAFRNG 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.
CALSOUR....List of sources for which calibration constants are to be
determined, i.e. the calibrator sources All ' ' = all
sources; a "-" before a source name. means all except ANY
source named. Note: solutions for multiple sources can
only be made if the sources are point sources at their
assumed phase center and with the flux densities given in
the source (SU) table.
TIMERANG...Time range of the data to be used. In order: Start day,
hour, min. sec, end day, hour, min. sec. Days relative to
reference date.
BCHAN......First channel to use. 0=>all.
ECHAN......Highest channel to use. 0=>all higher than BCHAN
GAINUSE....(multisource) version number of the CL table to apply to
the data. 0 => highest.
REFANT.....The desired reference antenna for phases.
SUBARRAY...Subarray number to use. 0=>all.
SEARCH.....List of Prioritized antennas to be used when APARM(9)>0.
This adverb supplements REFANT. It is recommended that
SEARCH be filled with a list of antennas whose order
reflects the user's notion of which baselines will be
easiest to find fringes on. All baselines to each antenna
in SEARCH will be searched in order looking for fringes.
All remaining baselines will then be searched. Choosing
SEARCH wisely will speed the FFT portion of FRING. The
antenna chosen in REFANT is treated as SEARCH(0), ie all
baselines to it are searched first.
SOLINT.....The solution interval (min.) You really should set this;
longer values are allowed beginning with 15OCT96.
0 => 10 minutes for all inputs
If SOLINT > Scan/2 (in Multisource) SOLINT = Scan.
Delay-rate control parameters:
DPARM......Delay rate parameters.
DPARM(1)...Number of baseline combinations to use in the initial,
coarse fringe search (1-3). Larger values increase the
point source sensitivity but reduce the sensitivity to
extended sources when an accurate model is not available.
0=>3.
DPARM(2)...The delay window to search (nsec) centered on 0 delay.
0 => full Nyquist range defined by the frequency spacing.
If DPARM(2) < 0.0 no delay search will be performed.
DPARM(3)...The rate window to search (mHz) centered on 0 rate.
0 => full Nyquist range defined by the integration time.
DPARM(4)...The minimum integration time of the data (sec);
0 => search the data to find the minimum integration
time.
The correct minimum of all baselines should be supplied.
DPARM(5)...If > 0 then don't do the least squares solution. If the
least squares solution is not done then only the coarse
search is done and much less accurate solutions are
obtained.
DPARM(6)...If > 0 then the output data will not be averaged in
frequency else, all frequencies in each IF will be
averaged. Affects single source files only.
DPARM(7)...If > 0 then the phase, rate and delays will not be
re-referenced to a common antenna. This option is only
desirable for VLBI polarization data.
DPARM(8)...DPARM(8)>0 allows zero'ing of RATE, DELAY, and/or PHASE
solutions. ** Note that the ZEROing is done _AFTER_ the
FRING solution is found, this is not the mechanism for
turning off the DELAY, RATE, or PHASE search, see
DPARM(2-3) for that capability. **
DPARM(8) value zero RATES? zero DELAYs? zero PHASEs?
0 No No No
1 Yes No No
2 No Yes No
3 Yes Yes No
4 No No Yes
5 Yes No Yes
6 No Yes Yes
7 Yes Yes Yes
SOURCES....Sources to calibrate. If this is left blank then all
the sources are calibrated at once using the INTERPOL
(i.e. CLCAL is only run once). If sources are listed
then CLCAL is run once for each source using the
interpolation method stated in INTERPOL. This
second option is recommended, see EXPLAIN file.
CHINC......< 0 -> 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.
INTERPOL...The type of interpolation to be applied to the SN table:
' ' = linear vector interpolation with no SN smoothing.
'2PT ' = linear vector interpolation with no SN smoothing.
'SELF' = Use only SN solution from same source which
is closest in time.
'SIMP' = Simple linear phase connection between SN phase
entries, assumes phase difference less than 180
degrees.
'AMBG' = Linear phase connection using rates to resolve
phase ambiguities.
'CUBE' = As AMBG but fit third order polynomial to phases
and rates.
BADDISK....A list of disk numbers to be avoided when creating scratch
files.
EXPLAIN SECTION
VLBAFRNG: Procedure to perform antenna based fringe fitting
using FRING and then apply these corrections using
CLCAL. If you are doing phase referencing use
VLBAFRGP.
Documenter: Amy Mioduszewski
Related Programs: VLBAUTIL, FRING, CLCAL, VLBAKRNG, VLBAFRGP
This should be done after solving for the instrumental phase
corrections (VLBAPCOR) and before applying all the calibration
and averaging (SPLIT/SPLAT). After VLBAFRNG is run it is ESSENTIAL
to check the solutions in POSSM setting GAINUSE to the CL table
output by VLBAFRNG. VLBAFRNG will produce the highest SN and
CL table. For details on FRING and CLCAL see their HELP/EXPLAIN
files.
VLBAFRNG assumes:
1. there is only one FREQID
2. that all IFs should be calibrated
3. that all antennas should be calibrated
4. that the entire uv range should be calibrated
5. that the highest FG table is the one that should be applied
6. that this is a multisource file
Steps in VLBAFRNG:
1. Runs FRING, which will do antenna based fringe fits. This
will produce the highest SN table.
2. Runs CLCAL, with OPCODE 'CALI', SNVER output SN table from
FRING; GAINVER input GAINUSE and GAINUSE = highest CL table +1.
Output should be highest CL table. If SOURCES is blank then
CLCAL is run only once. If SOURCES is not blank then CLCAL
will be run for each SOURCE individually setting both CALSOUR
and SOURCES to the same single source in the SOURCES list.
This is recommended because of CLCAL is run for all the sources
at once with any INTERPOL except 'SELF' then incorrect
solutions may be applied for a few minutes before and after a
source change. CLCAL will output the highest CL table.
After VLBAFRNG is run and the solutions are checked in POSSM SPLIT
or SPLAT should be run with GAINUSE set to the CL output from VLBAFRNG
and DOCAL=2.