Documentation on atlod

Task: atlod
Purpose: Convert an RPFITS file into Miriad uv format.
Categories: data transfer

        ATLOD is a MIRIAD task, which converts a uv data-set from the RPFITS
        format to Miriad format.

Key: in
        Name of the input RPFITS files. Several names can be given -- wildcard
        expansion is supported. If a single name is given, this can be a raw
        tape device name (e.g. /dev/nrst0 in UNIX) containing several files.
        In this case, see the NFILES keyword below. There is no default. 

Key: out
        Name of the output Miriad uv data-set. No default.

Key: ifsel
        IF number to select.  Default is all IFs.  For example,
        if you observed with 5 GHz (frequency 1) and 8 GHz (frequency 2) 
        simultaneously, IF 1 would be the 5 GHz data and IF 2 would 
        be the 8 GHz data.

Key: restfreq
        The rest frequency, in GHz, for line observations.  By default,
        the value in the RPFITS file is used.  Giving a value for the
        "restfreq" parameter overrides the RPFITS file value. If you
        do set this parameter, you MUST give the same number of values as the
        number of IFs written out. A value of 0 is used for a continuum
        observation. For example, if you have two IFs, the first of
        which is HI, and the second is continuum, use
            restfreq=1.420405752,0

Key: options
        This gives extra processing options. Several can be given,
        separated by comas.
          'birdie'  ATCA self-interference can corrupt channels at integral
                    multiples of 128 MHz. The birdie option flags these
                    channels. Additionally, in continuum (33 channels/128MHz)
                    mode, the birdie option dicards every second channel, plus
                    some edge channels. The channels discarded
                    are those most likely affected by the self-interference.
                    Discarding these channels does not have a
                    sensitivity penalty, because the effective channel
                    bandwidth is twice the channel separation.
          'reweight' Re-weight the lag spectrum to eliminate the "Gibbs" phenome
          'compress' Write output data in compressed format.
          'noauto'  Discard autocorrelation data. The default is to
                    copy the autocorrelation data.
          'nocross' Discard cross-correlation data. The default is to
                    copy the cross correlation data.
          'relax'   Do not flag visibilities based on SYSCAL information.
                    The default is to flag and drop visibilities if they have
                    not been preceded by a valid SYSCAL record, or if the
                    the values in the SYSCAL record look bad. SYSCAL
                    values are checked for sampler statistics being within
                    3% of 17.3%, or 0.5% of 50.0%, and that the XY phase
                    is within 10 degrees of the running median XY phase.
          'unflag'  Save any data that is flagged. By default ATLOD
                    discards most data that is flagged.
          'samcorr' Correct the pre-Dec93 data for incorrect sampler
                    statistics. Since December 1993, sampler corrections
                    are performed online -- Miriad ignores the samcorr
                    option for this data.
          'xycorr'  Apply the on-line measurement of the XY phase.
          'hanning' Hanning smooth spectra and drop every other channel
                    This option is ignored for 128-MHz, 33-channel data.
          'bary'    Use the barycentre as the velocity rest frame. The
                    default is to use the LSR frame.
          'noif'    Do not map the simultaneous IFs to the IF axis.
                    By default ATLOD attempts to map the simultaneous
                    frequencies to the IF axis. This will not be possible
                    if there are a different number of polarisations in
                    the different IFs.

Key: nfiles
        This gives one or two numbers, being the number of files to skip,
        followed by the number of files to process. This is only
        useful when the input is a tape device containing multiple files.
        The default is 0,1 (i.e. skip none, process 1 file).

        NOTE: Using this feature to skip many files on a tape is VERY
        inefficient. It is far faster to skip using operating system commands.
        When doing this, however, you should be aware is that every RPFITS files
        consists of 3 tape files. Thus you will want to skip three times as
        many tape files as RPFITS files. For example, in UNIX, to skip 10
        RPFITS files, use
                    mt -f /dev/nrst0 fsf 30

Key: nscans
        This gives one or two numbers, being the number of scans to skip,
        followed by the number of scans to process. NOTE: This applies to
        all files read. The default is to skip none and process all scans.