Basic Information on lagflg

Task: lagflg
Purpose: Flag visibility data in the lag domain.
Categories: calibration

        LAGFLG is a Miriad task to flag visibility data in the lag domain.
        As visibility flags are correlation-based (not lag based), this task
        has to produce a new outpput file.
 
        Ideally, the input visibility file would be before Hanning smoothing
        (if any), any calibration has been applied, and certainly before any
        subsetting of the visibility spectrum has been performed.
 
        This requires that the number of channels is 2**n+1, for some value of
        n.

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

Key: out
        Output visibility file, after flagging. No default.

Key: lags
        A list of pairs, giving the lags to be flagged. Each pair gives
        a range of lag values. These are indices, with the zero lag having
        the value 0. This is the same lag numbering system used by uvspec
        when displaying lags. No default - at least one range pair must be
        given.

Key: select
        Normal visibility selection. See the help on select for more
        information. All data in the input is copied to the output, but
        only those data selected using the select keyword will go through
        the lag flagging process. Currently only "polarization", "antenna"
        and "time" selection is supported in this task. This should be
        sufficient to select a correlator product that is bad over a
        particular period.

Key: options
        This gives extra processing options. Several options can be given,
        each separated by commas. They may be abbreviated to the minimum
        needed to avoid ambiguity. Possible options are:
          noflag    By default, "lagflg" zeros flagged data before it
                    transforms to the lag domain. At times this might
                    no be desirable - in which case use this option.