AIPS NRAO AIPS HELP file for VLBAKRNG in 31DEC18



As of Tue Jun 19 10:02:45 2018


VLBAKRNG: 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                           Subarray               0=>all
SEARCH            0.0     1000.0   Prioritized reference antenna
                                   list - supplements REFANT
SOLINT                             Solution interval (min)
                                   0 => 10 min
OPCODE                             'ZDEL' => zero delays
                                        for more, See HELP KRING
                                   FOR SPEC. LINE EXP. ONLY
CPARM                              for strong sources, it is
                                   only necessary to set
                                   CPARM(1) and CPARM(8).
                                   1 min. int. time (sec) 0 => 2
                                   8 <=0 rereference solutions
                                     this should be 1 for
                                     polarization experiments.
                                   for rest see HELP VLBAKRNG
SOURCES                            Source list to calibrate: If
                                   sources are listed they are
                                   each calibrated with separate
                                   runs of CLCAL
INTERPOL                           Interpolation function:
                                   '2PT','SIMP','AMBG','CUBE',
                                   'SELF'
BADDISK            0.0        15.0 Disk no. not to use for
                                      scratch files.

HELP SECTION

VLBAKRNG
Type: Procedure
Use:  This procedure does antenna based fringe fitting using KRING
      and then applies those corrections using CLCAL.  For more
      information on KRING and CLCAL see their respective HELP/EXPLAIN
      files.  If you are doing a phase reference experiment use
      VLBAKRGP.
      Type RUN VLBAUTIL to make the VLBAKRNG 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.  Note that
             the desired refant is not required to be the primary search
             antenna.  You should choose the REFANT to be an antenna
             that is present during most of the observation.
  SUBARRAY...Subarray number to use. 0=>all.
  SEARCH.....List of prioritized reference antennas to be used for
             fringe searching during the FFT stage.  KRING constructs
             an internal search list to determine the order in which to
             perform the FFTs.  This search list is constructed by first
             copying the elements of SEARCH.  Finally, all remaining
             antennas antennas are appended to the search list in
             numerical order.  You can limit the search to only the
             specified elements of the SEARCH list by setting CPARM(6).
             Only baselines where at least one antenna appears in the
             search list will be searched for fringes.
             You should explicitly order the antennas in terms of decreasing
             sensitivity if at all possible.
  SOLINT.....The solution interval.  Note that this is only a
             recommended solution interval.  The actual solution interval
             used by KRING will be changed in order to divide each scan
             evenly into an integral number of data chunks.
             SOLINT is in minutes; the default value (SOLINT=0) is 10
             minutes.  SOLINT values larger than 10 are reset to 10 minutes
             unless CPARM(9)>0.  NB: If SOLINT > 0.75*Scan, SOLINT = Scan.
  OPCODE.....Solution masking to be performed _after_ fringe-fitting
             ' '  no masking
             'ZPHS'  zero phases in output SN table
             'ZRAT'  zero rates in output SN table
             'ZDEL'  zero delays in output SN table
             If CPARM(8)>0, OPCODE is forced = ' '.
             If this is not a spectral line experiment leave this
             as the default.
  CPARM......CPARM(1) and CPARM(8) are the only CPARMs that it is essential
             to set, for strong sources the rest can be left as default.
  CPARM(1)...The minimum integration time of the data (sec);
             0 => 2 'VLBA' seconds
               It is important to get this number right to within 20  percent.
               E.g., if you've averaged up 1 second data to 10 seconds,
               setting this to 10 is okay so long as there are only a
               very few points with shorter than 10 second integration
               times.  If you set this to 1 second, you will regret it.
  CPARM(2)...The delay window FW to search (nsec) centered on 0 delay.
             <= 0 => full Nyquist range.
             [Use SOLMOD to turn off the delay search.]
  CPARM(3)...The rate window FW to search (mHz) centered on 0 rate.
             <= 0 => full Nyquist range.
             [Use SOLMOD to turn off the rate search.]
  CPARM(4)...The minimum allowed signal-to-noise ratio.  <0 => 3
             The SNR calculation is described in AIPS Memo 101.
             [You might consider setting this to 5.]
  CPARM(5)...Number of baseline combinations to use in the initial,
             FFT 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.
             [Solutions formed using combinations of baselines are
              marked with a plus for singly indirect combinations and
              with two pluses for doubly indirect combinations.]
  CPARM(6)...If CPARM(6)=1, only baselines to those antennas on the
             SEARCH list are searched during the FFT stage.  Otherwise,
             other baselines are eventually searched until either fringes
             have been found to each antenna, or no baselines remain to
             be searched.
  CPARM(7)...If >0, RR and LL data are averaged together and only a
             single solution is determined for both polarizations.  This
             is useful when reducing polarization data.
  CPARM(8)...If <= 0 then the phase, rate and delays will be
             re-referenced to a common antenna.  CPARM(8)=1 is only
             desirable for VLBI polarization data. Using this option also
             forces OPCODE = ' '.
  CPARM(9)...If SOLINT>10 is desired, you must set CPARM(9)>0 .  This
             is necessary to prevent accidentally requesting more memory
             than your computer can deliver and locking up computer.
  CPARM(10)..Try Hard Option.  If CPARM(10)>=0, When KRING is ready to
             do the initial FFT-based fringe search, it will first try
             to initialize residual fringe-fit delay and rate solns for
             each antenna using an average of all good solutions found
             in the SN table.  Only those antennas for which acceptable
             solutions are not found will then be FFTd to find fringes.
             This does not preclude the final Least Squares refinement.
             [20 Oct 1999, it has been reported that CPARM(10) is broken -
              it may trash the solutions - dont try it unless you have
              the time to re-run KRING if need-be.]
  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.
  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

VLBAKRNG:           Procedure to perform antenna based fringe fitting
                    using KRING and then apply these corrections using
                    CLCAL.  If you are doing phase referencing use
                    VLBAKRGP.
Documenter:         Amy Mioduszewski
Related Programs:   VLBAUTIL, KRING, CLCAL, VLBAFRNG, VLBAKRGP

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

VLBAKRNG 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 VLBAKRNG:

1. Runs KRING, 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
   KRING; 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 VLBAKRNG is run and the solutions are checked in POSSM  SPLIT
or SPLAT should be run with GAINUSE set to the CL output from VLBAKRNG
and DOCAL=2.

AIPS