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Section: User Commands (1)
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blflag - Interactive flagging task.  




uv analysis  


BLFLAG is a Miriad task for flagging visibilities interactively. It plots visibilities (e.g. amplitude vs time), either one baseline at a time or all together, and allows discrepant points to be flagged with a cursor.

Commands are entered as a single character at the keyboard:

  Left-Button  Left mouse button flags the nearest visibility.
  Right-Button Right mouse button causes BLFLAG to precede to
               the next baseline.
  <CR>         Carriage-return gives help.
  ?            Help.
  a            Flag nearest visibility (same as left mouse
  c            Clear the flagging for this baseline and redraw
  h            Give help (same as carriage return).
  p            Define a polygonal region, and flag visibilities
               within this region.  Define the vertices of the
               polygon by moving the cursor and then hitting the
               left mouse button (or a).  Finish defining the
               polygon by hitting the right mouse button (or x).
               You can delete vertices with the middle mouse
               button (or d).
  q            Abort completely.  This does not apply flagging.
  r            Redraw plot.
  u            Unzoom.
  x            Move to next baseline (same as right mouse
  z            Zoom in.  You follow this by clicking the mouse
               on the left and right limits to zoom.


Input visibility dataset to be flagged. No default.
The normal Miriad linetype specification. BLFLAG averages all channels together before displaying them, flags being applied to all channels. The default is all channels.
Normal PGPLOT plot device. An interactive device, e.g. /xserve, must be selected. No default.
Normal Stokes/polarisation parameter selection. The default is BLFLAG plots the average of all the selected Stokes/polarisation quantities. Also it flags ALL quantities, regardless of whether they were selected or not.
Normal visibility data selection. Only selected data can be flagged. The default is to select all data.
Two character strings, giving the X and Y axes of the plot. Possible axis values are:
  time         (the default for the X axis)
  lst          Local apparent sidereal time.
  uvdistance   sqrt(u**2+v**2)
  hangle       (hour angle)
  channel      (implies nofqav)
  amplitude    (the default for the Y axis)
  rms          Theoretical rms noise.
Plot range in the x-direction
  If axis = uvdistance            [kilo-lambda;   2 values]
  If axis = time                  [dd,hh,mm,ss.s; 8 values]
  If axis = amplitude, real, imag [natural units; 2 values]
  If axis = phase                 [degrees;       2 values]
  If axis = hangle                [hh,mm,ss.s;    6 values]
  If axis = rms                   [flux units;    2 values]
  If axis = lst                   [decimal hours; 2 values]
  If axis = freq                  [GHz;           2 values]

For axis types other than 'time' or 'hangle', one or other of the limits may be set with the other self-scaled by specifying the lower limit as 'min' and the upper as 'max' (or simply omitting it). For example,


self-scales the lower limit while pinning the upper limit to zero, whereas either of the following


set the lower limit to zero while self-scaling the upper limit.

Default is to self-scale both limits.

Plot range for the y-axis as for the x-axis. The default is to self-scale. For amplitude type plots you can greatly reduce the number of points to plot by using something like yrange=0.3 to cut out noise.
Task enrichment parameters. Several can be given, separated by commas. Minimum match is used. Possible values are:
  nobase  Normally BLFLAG plots a single baseline at a time.
          This option causes all baselines to be plotted on
          a single plot.
  selgen  Generate a file appropriate for selecting the bad
          data (via a "select" keyword).  The output is a text
          file called "".
  noapply Do not apply the flagging.
  rms     When processing spectra, blflag normally plots the
          mean value of the spectra.  Using options=rms causes
          it to plot the rms value instead.
  scalar  When processing spectra, blflag normally forms an
          average value by vector averaging.  This option
          causes it to generate the scalar average.  It should
          be used with significant caution.
  nofqaver Do not average spectra - the resulting number of
          points may be too large to handle.  Use select to
          break up the data in time ranges or use yrange to
          exclude noise.
The following options can be used to disable calibration.
  nocal   Do not apply antenna gain calibration.
  nopass  Do not apply bandpass correction.
  nopol   Do not apply polarisation leakage correction.

flag.for,v 1.5 2011/06/01 04:51:00 pteuben Exp $




This document was created by man2html, using the manual pages.
Time: 18:35:38 GMT, July 05, 2011