Documentation on blflag

Task: blflag
Purpose: Interactive flagging task.
Categories: uv analysis

        BLFLAG is an interactive flagger. BLFLAG plots the visibilities
        (e.g. time vs amplitude) either a baseline at a time or all at once,
        and allows you to flag discrepant points using the plotting cursor.
        There are a few simple flagging commands, which you enter as
        a single character at the keyboard. The following commands are
        possible:
          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.
          a	       Flag nearest visibility (same as left mouse button).
          c            Clear the flagging for this baseline, and redraw plot.
          h            Give help (same as carriage return).
          p            Define a polygonal region, and flag visibilities
                       within this region. You define the vertices of the
                       polygon by moving the cursor and then hitting the
                       left mouse button (or a). You 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.
          x            Move to next baseline (same as right mouse button).

Key: vis
        Input visibility dataset to be flagged. No default.

Key: line
        The normal Miriad linetype specification. BLFLAG will average
        all channels together before displaying them, and any flagging
        that you do will be applied to all selected channels. The default
        is all channels.

Key: device
        Normal PGPLOT plotting device. It must be interactive. No default.

Key: stokes
        Normal Stokes/polarisation parameter selection. The default
        is `ii' (i.e. Stokes-I assuming the source is unpolarised).
        NOTE BLFLAG plots the average of all the selected Stokes/polarisation
        quantities. Also it flags ALL quantities, regardless of whether they
        were selected or not.

Key: select
        Normal visibility data selection. Only selected data can be
        flagged. The default is to select all data.

Key: axis
        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)
          amplitude    (the default for the Y axis)
          phase
          real
          imaginary

Key: options
        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 "blflag.select".
          noapply Do not apply the flagging.
        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.