AIPS NRAO AIPS HELP file for RFLAG in 31DEC18



As of Tue Oct 16 11:34:07 2018


RFLAG: Flags data sets based on the cross-hand visibilities

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
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
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   If >0.5 apply bandpass cal.
                                   Method used depends on value
                                   of DOBAND (see HELP file).
BPVER                              Bandpass table version
SMOOTH                             Spectral smoothing function
                                   Dangerous here - see help.
OUTFGVER          0.0              Output flag table: 0 new
STOKES                             Stokes type ' ' => 'RLLR'
UVRANGE                            Restrict baselines in klambda
BIF                                Begin IF to process this time
EIF                                End IF to process this time
YINC                               Number of time samples
                                   averaged before algorithms
DCHANSEL                           Array of start and stop chan
                                   numbers, plus a channel
                                   increment and IF omitted from
                                   all operations.
ICHANSEL                           Array of start and stop chan
                                   numbers, plus a channel
                                   increment and IF to be used
                                   to select channels to sum to
                                   find spectral rms.
AVGCHAN           0.0    16384.0   Width of median window in
                                   the spectral flagging mode
DOSCALE          -1.0        1.0   > 0 -> determine relative
                                      gains first
DOPLOT          -16.0       16.0   > 0 -> plot, else flag data
                                      (see help)
                                   < 0 -> flag data, plot after
DOFLAG                             > 0 -> flag when DOPLOT > 0
FPARM                              (1) > 0 rolling T buffer to
                                      find time rms F(1) times
                                   (2) Normal time interval
                                      between samples (sec)
                                      IMPORTANT TO BE ~RIGHT
                                      and before time averaging
                                      with YINC
                                   (3) Maximum rms allowed in
                                      Jy in time rms
                                   (4) if not 0, do robust rms
                                      spectrally and flag
                                      channels deviating > F(4)
                                   (5) NEW - see HELP
                                      # channels taken from
                                      each spectral window
                                   (6) NEW - see HELP
                                      expand flagged region
                                   (7) flag whole spectrum if
                                      fraction flagged > F(7)
                                   (8) flag F(8) channels
                                      between flag groups
                                   (9) scale mean rms to compute
                                      NOISE,  0 -> 5.
                                   (10) scale mean deviation to
                                      compute SCUTOFF.   0 -> 5
                                   (11) Flag all baselines if
                                      a channel > F(11) flagged
                                   (12) Flag all baselines to an
                                      antenna if a channel >
                                      F(12) flagged
                                   (13) Flag any visibility amp
                                      > F(13) before time rms
                                      0 -> 1.E6
                                   (14) Flag times with fewer
                                      than F(14) baselines
                                   (15) Flag baseline if any vis
                                      > FPARM(15)
                                   (16) Flag both ants if any
                                      vis > FPARM(16)
                                   (20) >= 1 => flag only center
                                      time in bin
VPARM                              (1) Time rms upper limit to
                                      histogram (Jy) 0 -> 2
                                   (2) Spectral rms upper limit
                                      to histogram (Jy)
                                   (3) Plot only lower V(3)
                                      portion of plots 0 -> 1
                                   (4,5) Min/max time box to be
                                      plotted
                                   (6) Max Y time histogram
                                   (7) Max Y time cumulative
                                   (8,9) Min/max spectral box
                                     to be plotted
                                   (10) Max Y of spectral plot
                                   (11) Max Y cumulative spect.
                                   (12,13) min/max of average
                                     rms versus channel plot
                                   (14,15) min/max of average
                                     deviation vs channel plot
NOISE    $                         If FPARM(3) < 0, NOISE(i) is
                                   the max allowed in time rms
                                   for IF i (Jy)
                                   Returned when DOPLOT not 0
SCUTOFF  $                         If FPARM(4) < 0, SCUTOFF(i)
                                   is max allowed deviation in
                                   a channel for IF i (Jy)
                                   Returned when DOPLOT not 0
DOTV           -1.0         1.0    > 0 Do plot on the TV, else
                                   make a plot file
GRCHAN          0.0         7.0    Graphics channel 0 => several
LTYPE        -410.0       410.0    Type of labeling: 1 border,
                                   2 no ticks, 3 standard, 4 rel
                                   to center, 5 rel to subim cen
                                   6 pixels, 7-10 as 3-6 with
                                   only tick labels
                                   <0 -> no date/time
FUNCTYPE                           'LG' plot log of counts
                                   else plot is fully linear
XYRATIO         0.0                X/Y ratio 0 -> fit TV or
                                   1.414 PLot files
NBOXES          0.0      20000.0   Number histogram boxes
DOOUTPUT       -1.0          3.0   > 0, write OUTTEXT w weights
OUTTEXT                            Text file of channel weights
BADDISK                            Disks to avoid for scratch

HELP SECTION

RFLAG
Task:  This task examines SELECTED visibility spectra looking for RFI
       primarily.  It examines the rms versus time over short time
       intervals a polarization and a spectral channel at a time.
       Those exceeding user-specified threshold(s) are flagged in
       all polarizations.

       The task can pre-average over time (YINC intervals) on the fly
       before carrying out all algorithms.  Frequency averaging is
       accomplished with the SMOOTH adverb.  The task assumes that the
       times in the data set are approximately the same for all
       baselines.  Data sets produced by UBAVG (or procedure STUFFR)
       have averaged the data by different amounts depending on
       baseline length.  Even UVAVG can result in samples at quite
       different times for each baseline; OPCODE 'TIME' or 'GRID'
       should be used in UVAVG if the data are then to be given to
       RFLAG.

       Optionally, the robust average and rms of the real and
       imaginary parts of the visibility at each time are found in
       each IF individually.  Those channels deviating from this
       average by more than a user-specified cutoff in Jy are also
       flagged in all polarizations.

       To aid in setting the cutoff values, RFLAG can begin by
       computing histograms of the time rms and of the spectral
       deviations.  It can also compute means and rmses of the time
       rms and of the deviations from the spectral fits as a function
       of spectral channel and IF.  The computations done for the
       latter set adverb values (NOISE, SCUTOFF) which may be used for
       the actual flagging.  The histograms, cumulative histograms,
       and spectral functions may be plotted.  Following the plots,
       the program can go on to flag the data immediately or it can
       leave that operation for a later execution.

       Note that the cutoffs are all in Jy.  That may make particular
       values suitable only for sources within a modest range of
       fluxes.  RFLAG may then need to be used multiple times, once
       for strong calibrators, once for modest calibrators, and one
       more time for weak target sources.

       It may be better to use, e.g. 'RLLR' Stokes or 'QU' for this
       purpose than I which is likely to have larger signals perhaps
       made "noisier" by delay rocking and other gain-like errors.
       Stokes V may suffer from errors in calibration causing spurious
       values way larger than the true V polarization (if any).  Note
       one gotcha: if one of RR and LL is known to be bad, it has been
       traditional to flag it and both cross hands.  If you use only
       cross-hand polarizations, times previously flagged in this
       manner will not be examined.  STOKES='HALF' may be needed but
       with cutoff values different from when using STOKES='RLLR'.

       There are a large number of "knobs" in this task, so it may be
       best to suggest standard ways to use it.  You may wish however
       to consider many other choices.  In general, the first use of
       the task will be run first with DOPLOT = 12 to look at cutoff
       levels and spectral plots.  Then - without changing any other
       adverb - setting DOPLOT = -12 to apply the clip levels found in
       the first pass and then to compute a new set of clip levels.
       Leave DOFLAG=0 and let DOPLOT control whether flagging is
       actually done.

       FPARM is the main control adverb.
          FPARM(1) = 3 or 5
          FPARM(2) = normal interval between samples in sec
          FPARM(3) = -1   -> use NOISE(if number) to clip time rms
          FPARM(4) = -1   -> use SCUTOFF(if #) to clip frequency
                             spikes
                   = 0 for spectral-line data unless the channels are
                       known and DCHANSEL is set appropriately
          FPARM(5) = 0.001 -> evaluate each spectral channel against
                              its median and shift by 1 channel
          FPARM(6) = 1  -> flag one adjacent channel on each side of
                           flagged channels
          FPARM(7) = 0.85 -> if >= 85 percent of a channel is flagged, flag
                           all of that channel
          FPARM(8) = 2  -> if there are <= 2 channels between flagged
                           channels, flag them also
          FPARM(9) = 7  -> set clip levels at 7 * "rms" for NOISE
          FPARM(10) = 7  -> set clip levels at 7 * "rms" for SCUTOFF
          FPARM(11) = 0.75 -> if a channel is flagged in >= 75 percent of
                            baselines at a time, flag all baselines
                            for that channel
          FPARM(12) = 0.75 -> if a channel is flagged in >= 75 percent of
                            baselines to an antenna at a time, flag
                            that antenna for that channel
          FPARM(13) = 50  -> flag all data samples > 50 Jy before
                            doing any of this
          FPARM(14) = 20 -> flag any time/channel samples having fewer
                            than 20 baselines
       Usually one starts with corss-hand data STOKES='RLLR' but one
       may need to repeat with STOKES = 'HALF'.  Note that these
       values for FPARM(6) and FPARM(8) may be viewed as "harsh".

       If doing the spectral median filter, a largish AVGCHAN such as
       19 may be appropriate.

       VPARM controls the plots and usually can be left all zero.

       If you find that your clip levels must depend on UVRANGE, then
       you must separate wide-band data into separate files for each
       IF.  The UVRANGE test is based on the header frequency of a
       file and includes all spectral windows/channels for which the
       HEADER frequency gives a suitable baseline length.  (Note -
       this is true throughout AIPS.)
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.
  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.
  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.
  FLAGVER....specifies the version of the flagging table to be applied.
              0 => highest numbered table.
             <0 => no flagging to be applied.
             Keep track of your FG table versions to be certain that
             you are using all of the flags that you intend to use.
  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.
             NOTE: SMOOTH IS VERY DANGEROUS IN THIS CONTEXT.  IF ONE
             USES IT AND FLAGS SOME CHANNELS THE VALUES IN UNFLAGGED
             CHANNELS CHANGE MAKING RFLAG APPEAR TO HAVE NOT FLAGGED
             ALL THAT IT SHOULD HAVE.  If you realy need SMOOTH to
             remove ringing from narrow-band signals, run SPLAT on the
             data to apply the SMOOTH and then set SMOOTH=0 for later
             work.  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).
  OUTFGVER...Output flag table version.
             0 -> new version and the contents of FLAGVER are copied
                  to it initially.
             n = pre-existing file -> new flags are appended to the
                  OUTFGVER but FLAGVER is not copied.
             OUTFGVER may point to the same file as FLAGVER.  In that
             case, FLAGVER and any new flags are put in a temporary
             flag table and finally the temporary flag table replaces
             the input FLAGVER.
  STOKES.....Type of Stokes parameters to examine.  All Stokes will be
             flagged whenever one of the examined ones is deemed out
             of bounds.  ' ' => 'RLLR'
  UVRANGE....Restrict the examination of data to the specified range
             of baseline lengths in klambda at the reference
             frequency.  UVRANGE(2) <= UVRANGE(1) => UVRANGE(2)=1.E12
  BIF........First IF included in operation
  EIF........Last IF included in operation
             Plots sum the histograms over included channels and IFs
             but the time rms is done one spectral channel and IF at a
             time for computing the rms and for flagging and the
             spectral fitting is done one IF at a time.
  YINC.......Pre-average over YINC time samples before carrying out
             the other algorithms.  <= 0 -> 1.
  DCHANSEL...Array of start, stop, and increment channel numbers plus
             an IF used for channel DESELECTION.  Any group of
             channels specified will not be examined for time or
             spectral rms and will not be flagged except when the full
             spectrum is flagged.  Up to 20 sets of channels/IF may be
             entered.  The first having DCHANSEL(2,i) <= 0 terminates
             the list.  DCHANSEL(4,i) is the IF number, with <= 0
             meaning all.  If an IF has no DCHANSEL set for it, then
             all channels in the IF are included in the rms and
             flagging oprations.
  ICHANSEL.. Array of start, stop, and increment channel numbers plus
             an IF used for channel selection in the averaging to
             compute a spectral rms.  Up to 20 sets if channels/IF may
             be entered.  The first having ICHANSEL(2,i) <= 0
             terminates the list.  ICHANSEL(4,i) is the IF number,
             with <= 0 meaning all IFs.  If an IF has no ICHANSEL set
             for it, then ALL channels will be used.  Note that this
             is a non-standard default appropriate to the sliding
             median window method now used.
             For instance, if you wished to exclude channels 1 - 10
             and 121 - 128 because of bandpass effects, and channels
             56 - 80 of IF 1 but not IF 2 because of interference,
             then you would set ICHANSEL = 11,55,1,1, 81,121,1,1,
             11,121,1,2.  If you only wished to use every other
             channel from the second IF then you would set ICHANSEL =
             11,55,1,1, 81,121,1,1, 11,121,2,2.  if there are actually
             4 IFs, then IFs 3 and 4 would use channels 17 through
             112.  To set the channel range for all IFs to 14, 115
             enter ICHANSEL = 14,125.  To set the channel range for
             all IFs to 14-115 except IF 3 set ICHANSEL=14,115,1,0,
             23 45,1,3, 64,101,1,3 where the all IF part must come
             before the parts that partially override it.
  AVGCHAN....The spectral mode uses a median window AVGCHAN spectral
             channels wide where AVGCHAN is forced to be odd.  The
             default is one or two less than the full width of the
             spectrum.  The value at the center of the window is
             compared to the median value of the window and values
             more than FPARM(4) or SCUTOFF will be flagged.
  DOSCALE....> 0 -> Read the data through to find separate amplitude
             gains for each baseline and IF and apply those to the
             data when plotting and flagging.  The median amplitude of
             the channels in each spectral window at each sample is
             taken as the amplitude to be averaged over all times.
             <= 0 -> do not determine such gains and do not apply
             them.
  DOPLOT.....If DOPLOT > 0, histograms of the time rms and of the
             deviations from the spectral fit are computed.  Also
             computed are the mean time rms and the mean deviation
             from the spectral fit in each spectral channel.  These
             are then used to set the adverbs NOISE and SCUTOFF.
             If 16 > DOPLOT > 0, it is broken into a bit pattern and
             plots corresponding to the bits that have value are
             generated.
             bit 1 (1,3,5,...) => Plot the time rms and the spectral
                   deviations as histograms.
             bit 2 (2,3,6,...) => Plot the cummulative histograms
                   (fraction of data above x)
             bit 3 (4,5,6,...) => Plot the spectrum of time rms
                   (average and deviation in each channel) versus
                   channel
             bit 4 (8,9,10,..) => Plot the spectrm of deviation from
                   the spectral fit (average and rms) versus channel
             = 0 => Do not do the plots and do not change the input
             values of NOISE and SCUTOFF.
             DOPLOT < 0 => flag the data with FPARM and possibly NOISE
             and SCUTOFF.  Then plot the data using the new flag table
             with abs(DOPLOT) providing the plot control as above.
  DOFLAG.....If DOFLAG > 0 or DOPLOT <= 0, compute the time rmses and
             optionally spectral fits with deviations and generate
             flag table entries for the data in excess of the cutoffs.
             This means that one can
             (a) compute NOISE and SCUTOFF and then use them (or use
             FPARM(3) and/or FPARM(4)) (DOPLOT > 0, DOFLAG > 0);
             (b) use the input NOISE and SCUTOFF (or FPARM(3) and/or
             FPARM(4)) without changing them (DOPLOT <= 0, and any
             DOFLAG);
             (c) compute NOISE and SCUTOFF and generate plots (16 >
             DOPLOT > 0 and DOFLAG <= 0) with no flagging; and
             (d) compute NOISE and SCUTOFF and generate plots (DOPLOT
             >= 16 and DOFLAG <= 0) with no flagging;
             (e) use the input NOISE and SCUTOFF (or FPARM(3) and/or
             FPARM(4)) without changing them (DOPLOT < 0 and any
             DOFLAG) to flag the data follwoed by data plots generated
             with the new flag table.
  FPARM......(1) Number of times to be included in the time rms.  We
                 recommend an odd number and < 3 -> 3.
             (2) Normal interval between samples in seconds.  The
                 program will not do intervals longer than 2 *
                 FPARM(1) * FPARM(2).   0 -> 10 secs
                 IT IS IMPORTANT TO HAVE THIS ABOUT RIGHT.  If it is
                 too short, in particular, then data samples that
                 belong in the same bin (time interval) may end up in
                 different bins.  This happens most often when data
                 have been time averaged after selective flagging.
                 Set it to somewhat less than the averaging time -
                 if observations at XINT are averaged over N times,
                 set FPARM(2) = (N-0.5) * XINT.
                 Units are seconds and before any YINC averaging.
             (3) Flag all data having a time rms > FPARM(3) Jy.
                 0 -> 1.e6.  If FPARM(3) < 0.0, use NOISE(i) as the
                 clip level for IF i instead of FPARM(3).  If
                 ABS(FPARM(3)) >= 1.E6, the computation of time rms is
                 not done under any circumstances, so no time rms
                 flags, plots, and changed output NOISE values occur.
             (4) If FPARM(4) not 0, also do a median-window operation
                 over the spectral channels in each IF.  Flag those
                 channels which differ from the median by more than
                 FPARM(4) Jy when FPARM(4)>0.  If FPARM(4)<0, do this
                 flagging using IF-dependent values SCUTOFF(i) instead
                 of FPARM(4).  The computation is done separately for
                 the real and imaginary parts.  The width of the
                 window is set by AVGCHAN.  0 -> do not do the
                 spectral computation.
             (5) The center channel plus FPARM(5) channels on each
                 side of the central channel are evaluated from each
                 spectral median-filter window.  That window then
                 moves 1+2*FPARM(5) for the next evaluation - speeding
                 the spectral analysis process.  0 -> AVGCHAN/40,
                 -1 -> 0.  If AVGCHAN is say 101, then the default
                 would take 5 channels at a time centered in each
                 window and the next window would start 5 channels
                 later than the previous one.
             (6) After the time and spectral flagging is evaluated for
                 each time, expand each region of flagged channels by
                 FPARM(6) channels in each direction.  This occurs
                 before the application of the options in FPARM(7),
                 FPARM(8), FPARM(11), and FPARM(12).
             (7) If the fraction of channels to be flagged (and
                 previously flagged) in a given time and IF sample
                 exceeds FPARM(7), flag the whole thing.  Note that
                 this looks at the results of the time rms and the
                 spectral rms (if any) plus the FPARM(8) test.  It is
                 done both before and after the FPARM(10) test.  0->1
             (8) Flag up to FPARM(8) "good" channels located between
                 groups of flagged channels.  Thus if we are to flag,
                 for example, channels 12-14, 16-20, 23-24, and 28-30
                 and FPARM(7)=2, then we will flag 12-24 and 28-30.
             (9) When DOPLOT > 0, the program sums the time rmses in
                 each channel separately.  It then computes the mean
                 and rms of these time rmses in each channel and finds
                 the median average channel rms over each IF and its
                 variance.  Adverb NOISE(i) is set to FPARM(9) *
                 (median + variance).  0 -> 5.0 which seems to be a
                 good value.
             (10) When DOPLOT > 0, the program sums the deviations
                 from the spectral fit (if FPARM(4) not 0.0) in each
                 channel separately.  It then computes the mean  rms
                 of these deviations in each channel and finds the
                 median average channel deviation over each IF and its
                 variance.  Adverb SCUTOFF(i) is set to FPARM(10) *
                 (median + variance).  0 -> 5.0 which may be a good
                 value.
             (11) If a channel is flagged at one time in > FPARM(11)
                 fraction of the baselines, flag it in all baselines
                 at that time.   0 -> 1 => don't do this.
                 Note that autocorrelations are allowed, so the
                 maximum number of "baselines" is (Mant * (Mant+1)) /
                 2 where Mant is the maximum antenna number.  Thus the
                 EVLA with Mant = 28 has 406 "baselines" rather than
                 351 when antenna 28 is in the array.
             (12) If a channel is flagged at one time in > FPARM(12)
                 fraction of the baselines to a particular antenna,
                 flag it in all baselines to that antenna at that
                 time.   0 -> 1 => don't do this.
                 Note that autocorrelations are allowed, so the
                 maximum number of "baselines" to an antenna is the
                 maximum antenna number.
             (13) Examine the data before doing any other checks and
                 flag all samples > FPARM(13) Jy.  0 -> 1.E8.
             (14) Examine the data before doing any other checks and
                 flag all baselines when there are fewer than
                 FPARM(14) baselines with valid data, channel by
                 channel, IF by IF.  This is called a quack operation
                 but applies at any time, not just the start and end
                 of scans.
             (15) Examine the data before doing other checks and, if
                 any channel has amplitude > FPARM(15), flag all
                 channels in that baseline and IF.
             (16) Examine the data before doing any other checks and,
                 if any channel has amplitude > FPARM(16), flag all
                 channels in that IF for every baseline involving the
                 two antennas of the subject baseline.
             (20) >= 1.0 => flag only the center time in a time bin
                 when the time rms is excessive.  This is not
                 recommended when actually doing time rms flagging.
                 If FPARM(3) is very large so that only spectral
                 flagging is actually being done, this option may
                 speed the performance to the spectral code.
  VPARM......Plot controls when DOPLOT > 0:
             (1) Highest rms to histogram in the time-based rms's.
                 0 -> 2 Jy.
             (2) Highest deviation to histogram in the spectral
                 histogram.  0 -> 2 Jy
             (3) Plot only the lowest FPARM(10) portion of each plot
                 < 0.001 -> 1.0  Since you are usually interested only
                 in the lower portions, this option is quite useful.
             (4) Minimum time rms histogram box to plot
             (5) Maximum time rms histogram box to plot
                 If 0 < VPARM(4) < VPARM(5), the specified range of
                 boxes will be plotted.  Otherwise, the lowest box > 0
                 to the highest box > 0 is the range plotted.
             (6) > 0 -> Maximum value on Y axis for time rms
                 histogram before VPARM(3).
             (7) > 0 -> Maximum value on Y axis for time rms
                 cumulative histogram before VPARM(3).
             (8) Minimum spectral deviation histogram box to plot
             (9) Maximum spectral deviation histogram box to plot
                 If 0 < VPARM(8) < VPARM(9), the specified range of
                 boxes will be plotted.  Otherwise, the lowest box > 0
                 to the highest box > 0 is the range plotted.
             (10) Maximum value on Y axis of spectral deviation
                 normal histogram before VPARM(3).
             (11) > 0 -> Maximum value on Y axis for spectral
                 deviation cumulative histogram before VPARM(3).
             (12,13) Min and max of plot of mean time rms as a
                 function of channel.
             (14,15) Min and max of plot of mean spectral deviation as
                 a function of channel.
  NOISE......DOPLOT <= 0 : If FPARM(3) < 0, NOISE(i) will be used as
                the maximum allowed time rms for IF i.  Units are Jy.
             DOPLOT > 0  : Value of median time rms plus median rms of
                rmses times FPARM(9) in each IF.  NOISE is a returned
                adverb value not an input and is plotted as a straight
                line in each IF when bit 3 of DOPLOT is on
                (=4,5,6,..).  NOISE may then be applied (if FPARM(3) <
                0) in the same execution of RFLAG if DOFLAG > 0.
  SCUTOFF....DOPLOT <= 0 : If FPARM(4) < 0, SCUTOFF(i) will be used as
                the maximum allowed deviation from the spectral fit
                for IF i.  Units are Jy.
             DOPLOT > 0  : Value of median spectral deviation plus
                median rms of devaitions times FPARM(10) in each IF.
                SCUTOFF is a returned adverb value not an input and is
                plotted as a straight line in each IF when bit 4 of
                DOPLOT is on (=8,9,10,..).  SCUTOFF may then be
                applied in the same eecution of RFLAG to generate
                flags (if FPARM(4) < 0) if DOFLAG > 0.
  DOTV.......> 0 => plot directly on the TV device, otherwise make a
             plot file for later display on one or more devices
             (including the TV if desired).
  GRCHAN......Graphics channel (1 - 7) to use for line drawing.
              0 => use multiple graphics planes for the various parts
              of the graphical drawing.
  LTYPE.......Labelling type, see HELP LTYPE for details:
              1 = border, 2 = no ticks, 3 or 7 = standard, 4 or 8 =
              relative to ref. pixel, 5 or 9 = relative to subimage
              (BLC, TRC) center, 6 or 10 = pixels.  7-10 all labels
              other than tick numbers and axis type are omitted.
              Less than 0 is the same except that the plot file
              version number and create time are omitted.
              Add n * 100 to alter the metric scaling.
  FUNCTYPE....Histogram transfer function: 'LG' => log   else linear.
              X axis (rms in Jy and deviation in Jy) is linear.
  XYRATIO.....Scale the X axis longer than the Y by XYRATIO.
              If DOTV >  0, 0 -> fit to the TV window
              If DOTV <= 0, 0 -> 1.414.
  NBOXES......Number of cells for histogram.  20 <= nboxes <= 20000
              < 20 -> 200.
  DOOUTPUT....If DOPLOT > 0 and OUTTEXT is not blank and DOOUTPUT > 0,
              write a text file with channel dependent weights.
              DOOUT = 1 => use time rmses only
              DOOUT = 2 => use freq rmses only
              DOUUT = 3 or more => use both.
  OUTTEXT.....See DOOUTPUT above, gives path to desired text file.
  BADDISK....The disk numbers to avoid for scratch files.

EXPLAIN SECTION


AIPS