AIPS NRAO AIPS HELP file for IMFRING in 31DEC18



As of Fri Oct 19 17:57:24 2018


IMFRING: Determines antenna delays from large image

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 #
                                   input image
IN2NAME                               Large image name (name)
IN2CLASS                              Large image name (class)
IN2SEQ                                Large image name (seq #)
IN2DISK                               Large image name (disk)
BLC             0.0      4096.0    Bottom left corner of image
                                     0=>1
TRC             0.0      4096.0    Top right corner of image
                                     0=>max allowed
ICUT            0.0                Include all points > ICUT in
                                     absolute value only
FLUX                               Discard all points < FLUX
NX              1.0                Number panels in X
NY              1.0                Number panels in Y
OUTNAME                            name to use for temporary
                                   files (CC, OOSUB output)
OUTDISK                            Disk to put subimages/CCs
                                   Solution control adverbs:
DOKEEP            -1.0         1.0 > 0 -> keep divided us data
                                   Data selection (multisource):
BCHAN             0.0     2048.0   Lowest channel number 0=>all
ECHAN             0.0     2048.0   Highest channel number
ANTENNAS                           Antennas to select. 0=all
DOFIT                              Subset of ANTENNAS list
                                   for which solns are desired.
UVRANGE                            Range of uv distance for full
                                   weight
WTUV                               Weight outside UVRANGE 0=0.
WEIGHTIT          0.0        3.0   Modify data weights function
INVERS           -1.0    46655.0   CC file version #.
ONEFREQ          -1.0        1.0   > 0 => CC model from only
                                   one frequency (group)
CMETHOD                            Modeling method:
                                   'DFT','GRID','    '
                                   Solution control adverbs:
REFANT                             Reference antenna
SEARCH            0.0     1000.0   Prioritized reference antenna
                                   list - supplements REFANT
                                   - but only if APARM(9)>0
SOLINT                             Solution interval (min)
                                   0 => 10 min
SOLSUB                             Solution subinterval
SOLMIN                             Min solution interval

APARM                              General parameters
                                      1=min. no. antennas
                                      2 > 0 => data divided
                                      3 > 0 => avg. RR,LL
                                      4 > 0 => avg. freq. in IFs
                                      5 = 1 => combine all IFs
                                        = 2 => also MB delay
                                        = 3 => combine IFs in
                                               halves
                                        = 4 => combine IFs in
                                               thirds
                                        = N => combines IFs in
                                               N-1 pieces
                                        SEE HELP WARNING
                                      6=print level, 1=some
                                      7=SNR cutoff (0=>5)
                                      8=max. ant. # (no AN)
                                      9 > 0 => do exhaustive
                                               baseline search
                                     10 > 0 -> fit dispersion
                                        and IF group delay after
                                        fit of SB delays
DPARM                              Delay-rate parameters
                                      1=no. bl combo. (def=3)
                                      2=delay win (nsec), if <0
                                        no delay search done
                                      3=rate win (mHz)
                                      4=int. time (sec)
                                       0 => min. found in data
                                      5 >0 => don't do ls. soln
                                      6 >0 => don't avg. in freq
                                      7 >0 => don't rereference
                                        phase
                                      8 > 0 => activate zero'ing
                                                options
                                      9 > 0 => do not fit rate
ANTWT                              Ant. weights (0=>1.0)
BIF                                First IF included when
                                   APARM(5) > 0
EIF                                Last IF included when
                                   APARM(5) > 0
BPARM                              Task enrichment parameters
                                   (1) Antenna diameter (m)
                                        0 -> no correction
                                   (2) Omit CC options
                                   (3) spectral index radius
                                        0 -> no correction
FQTOL                              Frequency tolerance in kHz
                                   (primary beam & spec index)
IN3NAME                            Spectral index image name
IN3CLASS                           Spectral index image class
IN3SEQ                             Spectral index image sequence
                                   number
IN3DISK                            Spectral index image disk
IN4NAME                            Spectral curvature name
IN4CLASS                           Spectral curvature class
IN4SEQ                             Spectral curvature sequence
                                   number
IN4DISK                            Spectral curvature disk
BADDISK            0.0        15.0 Disk no. not to use for
                                      scratch files.

HELP SECTION

IMFRING
Task:  IMFRING is a procedure that combines IM2CC, OOSUB, FRING, and
       finally TACOP.  IM2CC breaks a large (usually CASA) image into
       pieces, making both an image and a Clean components table for
       each piece.  This is needed to allow AIPS to use its geometries
       while CASA has used the W-projection geometry.  OOSUB divides
       the data for a calibration source by the model from these
       pieces plus options to permit frequency-dependent primary beam
       and spectral index corrections.  CALIB then determines an
       IF-dependent delay and phase, using the divided data.  A
       solution (SN) table is written and copied to the input uv file
       by TACOP.  Finally the temporary, divided data set is deleted
       (optionally) and the image pieces are deleted..

       This procedure does not apply data selection and calibration
       adverbs to the input data set.  You must apply these with SPLIT
       or SPLAT (or other tasks) to make a data set consisting solely
       of the edited/calibrated data that you wish to self-cal.

       IMFRING makes a number of temporary files all of which are
       assigned specific names including sequence number 1.  It will
       check for the presence of any of these on your disks before
       doing work.  If any are present, IMSCAL will list them and
       quit, allowing you to rename them or delete them.

       This procedure is obtained by entering RUN OOCAL.

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.
        **** Model image in Jy/pixel (not convolved with beam) ****
  IN2NAME....Input image file name (name).    Standard defaults.
  IN2CLASS...Input image file name (class).   Standard defaults.
  IN2SEQ.....Input image file name (seq. #).  0 -> highest.
  IN2DISK....Disk drive # of input image.  0 -> any.
  BLC........The bottom left-hand pixel of the input image which
             becomes the bottom left corner of the subimage from
             which the NX x NY panels are taken.   0 -> 1.
  TRC........The top right-hand pixel of the input image which
             becomes the top right corner of the subimage from which
             the panels are taken.  0 -> max allowed value.
  ICUT.......CC components are made only from pixel values greater in
             absolute value than ICUT and
  FLUX.......CC components are made only from pixel values greater
             than FLUX (in actual value).  Thus FLUX=0 cuts off all
             negatives.
  NX.........The X axis is divided into NX nearly equal panels.
  NY.........The Y axis is divided in NY nearly equal panels.
             Be sure to make enough to account for any W term issues.
  OUTNAME....The output subimages are stored on OUTDISK with this name
             parameter.  The OUTSEQ=1 and OUTCLASS=IMCnnn.  The output
             from the OOSUB step in OOCAL also uses this name with
             OUTCLASS 'OOCAL1'.
  OUTDISK....The output subimages and CC files are put on OUTDISK, the
             OOSUB output file is put on INDISK.  It is better to
             avoid Lustre disks for the CC files.
  DOKEEP.....> 0 => keep the file produced by OOSUB containing the
                    input data divided by the model and the SN table
                    produced by CALIB
             <=0 => delete this temporary file after TACOP.

  BCHAN......First channel to use. 0=>all.
  ECHAN......Highest channel to use. 0=>all higher than BCHAN
  ANTENNAS...A list of the antennas to  have solutions determined. If
             any number is negative then all antennas listed  are NOT to
             be used to determine solutions and all others are. All 0 =>
             use all.
  DOFIT......A list of the antennas for which solutions should or
             should not be determined.  If DOFIT = 0, all antennas are
             solved for.  If any entry <= -1, , then DOFIT is taken as
             the list of antennas for which no solution is desired; a
             solution is found for all antennas not in DOFIT.  If any
             entry of DOFIT is non-zero and all are >= 0, then only
             those antennas listed in DOFIT will be solved for - all
             other selected antennas will not be solved for.
             NOTE: THIS OPTION MUST NOT BE USED UNLESS YOU UNDERSTAND
             IT FULLY.  Basically, it should be used to solve for the
             gains of "poor" antennas after the "good" antennas have
             been fully calibrated.  Antennas included in ANTENNAS but
             not in DOFIT are assumed to have a complex
             gain/delay/rate of (1,0,0,0) and the gains/delays
             produced will be very wrong if this is not the case.
             See HELP DOFIT.
The following may be used for all data files (except as noted):
  UVRANGE....The range of uv distance from the origin in kilowavelengths
             over which the data will have full weight; outside of this
             annulus in the uv plane the data will be down weighted by a
             factor of WTUV.
  WTUV.......The weighting factor for data outside of the uv range
             defined by UVRANGE.
  WEIGHTIT...If > 0, change the data weights by a function of the
             weights just before doing the solution.  Choices are:
             0 - no change   weighting by 1/sigma**2
             1 - sqrt (wt)   weighting by 1/sigma may be more stable
             2 - (wt)**0.25
             3 - change all weights to 1.0
  ONEFREQ....In IMAGR, a CC file is made from the "average" of all
             channels included in the bandwidth synthesis.  But it is
             also possible to make the model image(s) from a single
             frequency (or from frequencies within FQTOL anyway).
             Set ONEFREQ = 1 if the model was made this way, leave it
             zero if all frequencies were included in the model.
  CMETHOD....This determines the method used to compute the model
             visibility values.
             'DFT' uses the direct Fourier transform, this method is
                   the most accurate.
             'GRID' does a gridded-FFT interpolation model computation
             '    ' allows the program to use the fastest method
The following control how the solutions are done, if you don't
understand what a parameter means leave it 0 and you will probably get
what you want.
  REFANT.....The desired reference antenna for phases.
  SEARCH.....List of Prioritized antennas to be used when APARM(9)>0.
             This adverb supplements REFANT.  Along with APARM(9)>0,
             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.
  SOLSUB.....The begin time for the next interval in advanced from the
             current one by SOLINT / SOLSUB where 1 <= SOLSUB <= 10.
             0 -> 1.  This is to produce solutions at sub-intervals of
             SOLINT based on SOLINT length of averaging.
  SOLMIN.....Minimum number of subintervals to be used in a solution.
             0 -> SOLSUB.
  APARM......General control parameters.
  APARM(1)...Minimum number of antennas allowed for a solution. 0 => 3.
  APARM(2)...If > 0 then the input data has already been divided by a
             model; only solutions will be determined.
  APARM(3)...If > 0 then average RR, LL
  APARM(4)...If > 0 average all frequencies in each IF before the
             solution and in the output for single source files.
  APARM(5)...WARNING: IF THE FREQUENCY INCREMENT BETWEEN IFS THAT WILL
             BE INCLUDED IN A GROUP HAS THE OPPOSITE SIGN FROM THE
             FREQUENCY INCREMENT BETWEEN CHANNELS IN THE IFS OF THAT
             GROUP, YOU SHOULD NOT USE THE FOLLOWING
                  (SET APARM(5)=0 ONLY).
             If = 1 then make a combined solution for the IFs;
             If <= 0 then make separate solutions.
             If = 2 do separate least squares fits for single- and
                  multi-band delays.  This option will override APARM(4)
                  > 0. WARNING: multi-band delays derived by this method
                  cannot be smoothed.
             If = 3 then make solutions combining IFs 1 through NIF/2
                  and IFs NIF/2+1 through NIF.  This may be appropriate
                  for the EVLA in which the first NIF/2 are from
                  hardware IF AC and the others are from hardware BD.
             If = 4 then make solutions combining IFs 1 through NIF/4,
                  NIF/4+1 through NIF/2, NIF/2+1 through 3*(NIF/4),
                  and IFs 3*(NIF/4)+1 through NIF.  This may be
                  appropriate for the EVLA for 3-bit sampling in which
                  each quarter passes through separate hardware and
                  hence has separate delay errors.
             NOTE - APARM(10) can partly override this - causing the
             task to fit a delay in each IF and then to fit a
             dispersion across all IFs plus delay for each group of
             IFs.  The output SN table will contain dispersion values
             plus the single-band delays and phases corrected for the
             dispersion.
  APARM(6)...Print flag, -1=none, 0=time every 10th time, 1=time,some
             info, 2=more including the antenna signal to noise ratio,
             3=a very great deal.
  APARM(7)...The minimum allowed signal-to-noise ratio.   0 => 5
  APARM(8)...If there is no antenna (AN) table with the input file then
             the maximum antenna number in the file should be entered in
             APARM(8).
  APARM(9)...If > 0, perform exhaustive baseline search in the initial
             FFT stage.  Normally, the first stage of FRING is to FFT
             individual baselines searching for initial estimates of the
             residual phases, rates, and delays.  This stage is notable
             in that FRING gives up too easily - only baselines to the
             user-selected REFANT and one other antenna are searched.
             APARM(9)>0 instructs FRING to exhaustively search for
             initial estimates for each antenna's errors.  See SEARCH
             above as well.
  APARM(10)..If > 0, causes the task to fit a delay in each IF and then
             to fit a dispersion plus a delay for each group of IFs to
             the SB delays in all IFs.  The output SN table will
             contain dispersion values plus the single-band delays and
             phases corrected for the dispersion.
  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
  DPARM(9)...> 0 => supress fitting for rate (rather than just zero
             the fit afterwards).  This assumes that the true rate is
             small and causes all the data in SOLINT to be averaged
             before being fed to the fitter.  DPARM(8)=1 is not needed
             in this case.
  ANTWT......Antenna weights.  These are additional weights to be
             applied to the data before doing the solutions, one per
             antenna.  Use PRTAN to determine which antenna numbers
             correspond to which antennas.
  BIF........First IF included when APARM(5)=1,3,4 (all IFs receive the
             solution found for the appropriate group of IFs, but only
             BIF-EIF are used to find it).
  EIF........Last IF included when APARM(5)=1,3,4 (all IFs receive the
             solution found for the appropriate group of IFs, but only
             BIF-EIF are used to find it).
  BPARM......Correction control parameters (SEE EXPLAIN IMAGR):
             (1) If > 0 then make frequency dependent primary beam
               corrections assuming an antenna diameter of IMAGRPRM(1)
               meters.  Note that VLA and ATCA arrays (TELESCOPE
               header parameter) use the default primary beam
               parameters defined elsewhere in AIPS, while other
               antennas actually use IMAGRPRM(1) as the diameter of a
               "standard" telescope.  See FQTOL below also.
             (2) If BPARM(1) > 0, you may omit selected CCs from the
               operation based on position:
                  BPARM(2) <= 0  : Include all CCs
                            = 1  : Omit CCs within the main beam at
                                   all frequencies
                            = 2  : Omit CCs within the main beam at
                                   some frequncies
                            = 3  : Omit Ccs outside the main beam at
                                   some frequencies
                            = 4  : Omit CCs outside the main beam at
                                   all frequencies
             (3) 1 => use a spectral-index image represented in
               IN3NAME, IN3CLASS, IN3SEQ, IN3DISK below to correct the
               Clean component model for each channel.  IN4NAME et al
               will also be used as a curvature image iff IN3NAME are
               specified.
               BPARM(3)-0.5 is used as a radius in pixels over which
               the spectral index image is averaged.  When it is small
               (0 < BPARM(3) <~ 1), the spectral index is interpolated
               rather than averaged.  See FQTOL below as well.  When
               doing spectral index, the primary beam correction
               (BPARM(1)) costs very little extra.  This parameter is
               IMAGRPRM(17) in IMAGR.
  FQTOL......Frequency tolerance in kHz.  Spectral channels with FQTOL
             are handled together (use the same average CC model) when
             applying the primary beam and spectral index
             corrections.  Default is to do each channel separately
             which can take a long time.
  IN3NAME....Image name of spectral index image; no default.
  IN3CLASS...Image class of spectral index image; no default.
  IN3SEQ.....Image sequence of spectral index image; 0 -> highest.
  IN3DISK....Disk of spectral image image; 0 -> any.
  IN4NAME....Image name of spectral index curvature image; no default.
             Curvature images should be base 10 rather than base e -
             they differ by a factor of 2.3.  Also the reference
             frequency is 1.0 GHz.  These are changes done 2010-07-13.
  IN4CLASS...Image class of spectral index curvature image; no
             default.
  IN4SEQ.....Image sequence of spectral index curvature image;
             0 -> highest.
  IN4DISK....Disk of spectral curvature image image; 0 -> any.
  BADDISK....A list of disk numbers to be avoided when creating scratch
             files.

EXPLAIN SECTION


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