As of Tue Jun 18 20:03:39 2024

VLBAFRGP: Procedure to fringe fit and calibrate phase ref. data


                                   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
                                   NO DEFAULT
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
                                   for rest see HELP VLBAFRGP
SOURCES                            Source list to calibrate: Any
                                   sources in the SOURCE list
                                   that are not in the CALSOUR
                                   list will be phase referenced
                                   to the FIRST source in the
                                   CALSOUR list.
CHINC                        1.0   Channel increment in FRING
                                   < 0 -> find from data
INTERPOL                           Interpolation function:
BADDISK            0.0        15.0 Disk no. not to use for
                                      scratch files.


Type: Procedure
Use:  This procedure does antenna based fringe fitting for phase
      referencing experiments using FRING and then applies those
      corrections using CLCAL.  For more information on KRING and
      CLCAL see their respective HELP/EXPLAIN files.
      Type RUN VLBAUTIL to make the VLBAFRGP procedure
  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. The default is not permitted nor are '-'
             sources, as you must select a phase reference source.  The
             FIRST source in the list is the phase reference source and
             will be used to phase reference any sources in the SOURCES
             list that are NOT in the CALSOUR list.
  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.  If this is not a spectral
             line experiment, leave as default.
  ECHAN......Highest channel to use. 0=>all higher than BCHAN. If this
             is not a spectral line experiment, leave as default.
  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.
  DPARM......Delay rate parameters.  For strong sources the only
             essential DPARMS are 4, 7 and 8.  8 is only important
             for spectral line experiments.
  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.
  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
             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
  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) and phase referenced to the
             FIRST source in the CALSOUR list.  If sources are listed
             then CLCAL is run once for each source using the
             interpolation method stated in INTERPOL.  Any sources
             that are in the SOURCE list but not in the CALSOUR list
             will be phase referenced to the FIRST source in the
             CALSOUR list.
  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
             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.
             'SIMP' = Simple linear phase connection between SN phase
                      entries, assumes phase difference less than 180
             '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


VLBAFRGP:           Procedure to perform antenna based fringe fitting
                    for phase referenced data using FRING and then apply
                    these corrections using CLCAL.
Documenter:         Amy Mioduszewski

This should be done after solving for the instrumental phase
corrections (VLBAPCOR) and before applying all the calibration
and averaging (SPLIT/SPLAT).  After VLBAFRGP is run it is ESSENTIAL
to check the solutions in POSSM setting GAINUSE to the CL table
output by VLBAFRGP.  VLBAFRGP will produce the highest SN and
CL table.  For details on FRING and CLCAL see their HELP/EXPLAIN

It should be noted that this procedure will do the same thing as
VLBAFRNG if all SOURCES are in the CALSOUR list.  In order to have
the target source phase referenced it must be missing from the CALSOUR
list and in the SOURCES list or, alternatively, the SOURCES list must be
left blank.  The first option caused the sources listed in SOURCES but
missing from CALSOUR to be phase referenced to CALSOUR(1), while the
second caused ALL the sources to be phase referenced to CALSOUR(1).

VLBAFRGP 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 VLBAFRGP:

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 and phase referenced to CALSOUR(1).  If
   SOURCES is not blank then CLCAL is run for each source in
   SOURCES.  If the source in SOURCES is in the CALSOUR list then
   it is referenced to itself, if not it is phase referenced to

After VLBAFRGP is run and the solutions are checked in POSSM  SPLIT
or SPLAT should be run with GAINUSE set to the CL output from VLBAFRGP
and DOCAL=2.