AIPS NRAO AIPS HELP file for BPWGT in 31DEC18



As of Mon Jul 23 9:35:59 2018


BPWGT: Calibrate data, scales weights by bandpass correction

INPUTS

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 #
SOURCES                            Source name
QUAL            -10.0              Calibrator qualifier -1=>all
CALCODE                            Calibrator code '    '=>all
STOKES                             Stokes of output
TIMERANG                           Time range to use
SELBAND                            Bandwidth to select (kHz)
SELFREQ                            Frequency to select (MHz)
FREQID                             Freq. ID to select.
SUBARRAY          0.0     1000.0   Sub-array, 0=>all
BIF                                Low IF number to do
EIF                                Highest IF number to do
BCHAN             0.0              First channel included
ECHAN             0.0              last channel included
DOCALIB          -1.0      101.0   > 0 calibrate data & weights
                                   > 99 do NOT calibrate weights
GAINUSE                            CL (or SN) table to apply
DOPOL            -1.0       10.0   If >0.5 correct polarization.
PDVER                              PD table to apply (DOPOL>0)
BLVER                              BL table to apply.
FLAGVER                            Flag table version
DOBAND            1.0       10.0   Must apply BP correction
                                   Method used depends on value
                                   of DOBAND (see HELP file).
BPVER                              Bandpass table version
SMOOTH                             Smoothing function. See
                                   HELP SMOOTH for details.
DOACOR                             Include autocorrelations?
OUTNAME                            Output UV file name (name)
OUTCLASS                           Output UV file name (class)
OUTSEQ           -1.0     9999.0   Output UV file name (seq. #)
OUTDISK           0.0        9.0   Output UV file disk unit #.
WEIGHTIT          0.0        2.0   0 - use BP, 1 - use sqrt(BP),
                                   2 - use BP^0.25
FQCENTER                           >= 0 -> center frequency axis
BADDISK                            Disks to avoid for scratch

HELP SECTION

BPWGT
Task:  Normally, the signal-to-noise ratio of spectral data is assumed
       to be independent of channel except for the outermost 1 or 2
       channels (which are affected by aliasing).  It is widely seen
       however that the noise in the outer channels after bandpass
       correction is rather larger than in the central channels.  This
       task allows the user to presume instead that the noise is the
       same in each spectral channel BEFORE application of the
       bandpass correction.  It will copy the data applying
       calibration and changing the weights by a factor of one over
       the bandpass amplitude correction squared.  Use this task as a
       form of SPLIT to apply the bandpass (and other) calibrations if
       you wish to down-weight the outer channels in this way.

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.
  SOURCES....Source to be copied.   '  '=> all; if any starts with a
             '-' then all except ANY source named.
  QUAL.......Qualifier of source to be copied. -1 => all.
  CALCODE....Calibrator code of sources to copy. ' '=> all.
  STOKES.....Specifies which STOKES parameters are written in the
             output data set:  ' ' => 'FULL'
               'I','Q','U','V', 'IV', 'IQU', 'IQUV'
               'RR','LL', 'RL', 'LR', 'RRLL', 'RLLR', 'RLRL'
               'XX','YY', 'XY', 'YX', 'XXYY', 'XYYX', 'XYXY'
             'HALF', 'CROS', and 'FULL' have sensible interpretations
             depending on the Stokes present in the data.  The last in
             each of the 3 rows above == 'FULL'.  Note that many
             combinations of polarizations in the input and values
             above are not supported.
  TIMERANG...Time range of the data to be copied. In order: Start day,
             hour, min. sec, end day, hour, min. sec. Days relative to
             ref. date.
  SELBAND....Bandwidth of data to be selected. If more than one IF is
             present SELBAND is the width of the first IF required.
             Units = kHz. For data which contain multiple
             bandwidths/frequencies the task will insist that some form
             of selection be made by frequency or bandwidth.
  SELFREQ....Frequency of data to be selected. If more than one IF is
             present SELFREQ is the frequency of the first IF required.
             Units = MHz.
  FREQID.....Frequency identifier to select (you may determine which is
             applicable from the OPTYPE='SCAN' listing produced by
             LISTR). If either SELBAND or SELFREQ are set, their values
             override that of FREQID.  However, setting SELBAND and
             SELFREQ may result in an ambiguity.  In that case, the task
             will request that you use FREQID.
  SUBARRAY...Sub-array number to copy. 0=>all.
  BIF........First IF to include.  0 -> 1.
  EIF........Last IF to include.   0 -> max.
  BCHAN......First channel to copy. 0=>all.
  ECHAN......Highest channel to copy. 0=>all higher than BCHAN
  DOCALIB....If true (>0), calibrate the data using information in the
             specified Cal (CL) table for multi-source or SN table for
             single-source data.  Also calibrate the weights unless
             DOCALIB > 99 (use this for old non-physical weights).
  GAINUSE....version number of the CL table to apply to multi-source
             files or the SN table for single source files.
             0 => highest.
  DOPOL......If > 0 then correct data for instrumental polarization as
             represented in the AN or PD table.  This correction is
             only useful if PCAL has been run or feed polarization
             parameters have been otherwise obtained.  See HELP DOPOL
             for available correction modes: 1 is normal, 2 and 3 are
             for VLBI.  1-3 use a PD table if available; 6, 7, 8 are
             the same but use the AN (continuum solution) even if a PD
             table is present.
  PDVER......PD table to apply if PCAL was run with SPECTRAL true and
             0 < DOPOL < 6.  <= 0 => highest.
  BLVER......Version number of the baseline based calibration (BL) table
             to apply. <0 => apply no BL table, 0 => highest.
  FLAGVER....specifies the version of the flagging table to be applied.
              0 => highest numbered table.
             <0 => no flagging to be applied.
  DOBAND.....If true (>0) then correct the data for the shape of the
             antenna bandpasses using the BP table specified by BPVER.
             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.
             IMAGR uses DOBAND as the nearest integer; 0.1 is therefore
             "false".
  BPVER......Specifies the version of the BP table to be applied
                0 => highest numbered table.
               <0 => no bandpass correction to be applied.
  SMOOTH.....Specifies the type of spectral smoothing to be applied to
             a uv database . The default is not to apply any smoothing.
             The elements of SMOOTH are as follows:
             SMOOTH(1) = type of smoothing to apply: 0 => no smoothing
               To smooth before applying bandpass calibration
                 1 => Hanning, 2 => Gaussian, 3 => Boxcar, 4 => Sinc
               To smooth after applying bandpass calibration
                 5 => Hanning, 6 => Gaussian, 7 => Boxcar, 8 => Sinc
             SMOOTH(2) = the "diameter" of the function, i.e. width
               between first nulls of Hanning triangle and sinc
               function, FWHM of Gaussian, width of Boxcar. Defaults
               (if < 0.1) are 4, 2, 2 and 3 channels for SMOOTH(1) =
               1 - 4 and 5 - 8, resp.
             SMOOTH(3) = the diameter over which the convolving
               function has value - in channels.  Defaults: 1,3,1,4
               times SMOOTH(2) used when input SMOOTH(3) < net
               SMOOTH(2).
  DOACOR.....> 0 => include autocorrelations as well as cross
             correlation data.
  OUTNAME....Output UV file name (name).     Standard defaults.
  OUTCLASS...Output UV file name (class).    Standard defaults.
  OUTSEQ.....Output UV file name (seq. #).   0 => highest unique
  OUTDISK....Disk drive # of output UV file. 0 => highest with space
             for the file.
  WEIGHTIT...If > 0, change the data weights by a function of the
             bandpass amplitude.  Choices are:
             0 - weight = weight_in / (BPamp)**2
             1 - weight = weight_in / (BPamp)
             2 - weight = weight_in / (BPamp)**0.5
             Value 0 corresponds to the assumption that the noise is
             independent of channel before applying the bandpass
             calibration which is a multiplication by "BPamp".
  FQCENTER,..>  0 => Change frequency axis reference pixel to
                     Nchan / 2 + 1
             else => do not change reference pixel
  BADDISK....The disk numbers to avoid for scratch files (sorting
             tables mostly).

EXPLAIN SECTION


AIPS