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Basic Information 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 it
        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(s) 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.  This now also lets you select zoom bands
        using values greater than 2.  The freq 1 zoom bands come before
        the freq 2 ones.

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'  For CABB data:
                    CABB generates self-interference in a number of
                    channels across the spectrum due to 640 MHz clock
                    harmonics.  These birdies are fixed in channel
                    number for each CABB configuration.  The birdie
                    option currently knows about the 2048x1MHz continuum
                    mode and flags the affected channels, 100 band edge
                    channels on each side, and, at 20 and 13cm, the
                    unusable parts of the spectrum.
 
                    For pre-CABB data:
                    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' For pre-CABB data: re-weight the lag spectrum to
                    eliminate the "Gibbs" phenomena in continuum data
                    (33 ch/128 MHz); ignored for all other data.
          '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 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%, that the XY phase is within 10 degrees of its
                    running median, and that the XY amplitudes are
                    within 1 Jy or 10% of its running median.  The tests
                    for xy phase and amplitude are skipped for 3mm data
                    (as there is no noise calibration signal).
          'mmrelax' This option is ignored, it is only present for
                    historical reasons.
          'unflag'  Save any data that is flagged and also keep it's
                    syscal info.  By default ATLOD discards most data
                    that is flagged.
          'opcorr'  Correct for atmospheric opacity.  This option is
                    possible for data measured after October 2003.
                    Because of the way system temperature is measured at
                    3mm (an "above atmosphere" measurement), it is not
                    appropriate for 3mm data.  This option is silently
                    ignored for 3mm data.  Generally it is only relevant
                    for 7mm and 12mm observations.  It does no harm (and
                    negligible good) for longer wavelengths.
          'samcorr' Correct the pre-Dec93 data for incorrect sampler
                    statistics.  Since December 1993, sampler
                    corrections are performed online.  This option is
                    silently ignored for data measured after December
                    1993.
          'xycorr'  Apply the on-line measurements of the XY phase.
                    This option is silently ignored for 3mm data
                    measured before October 2007.
          '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.
          'nopflag' If at least one polarisation of a set of 2 or 4
                    polarimetric spectra are bad, ATLOD normally flags
                    all of the polarisations.  Option nopflag changes
                    this so that only the nominally bad spectrum is
                    flagged.
          'hires'   Treat bin data as measurements in the high time
                    resolution mode.  The output dataset contains no
                    bins, but instead appears as data measured with
                    small cycle times.
          'pmps'    Undo `poor man's phase switching'.  This is an
                    obscure option that you should not generally use.
          'single'  Assume input is a single dish RPFITS file (from
                    Parkes or Mopra).  This is usually used together
                    with option 'relax'.
          'caldata' Save visibilities associated with certain system
                    calibrations.  Currently this consists of reference
                    pointing calibration and "paddle" measurements.
          'nocacal' Flag data that atlod suspects is taken during a
                    CACAL scan.  There is potential for error in atlod
                    determining which data are and are not part of a
                    cacal scan.  Use this with caution.
          'nopol'   Discard data that is not "parallel hand" Stokes
                    type.
          'rfiflag' Flag channels at frequencies that are known to be
                    bad.  This uses the file rfiflag.txt in the current
                    directory or the default version in MIRCAT.  The
                    file should contain 2 frequencies per line, the
                    lower and upper end of the rfi in MHz.  Precede
                    comments with a '#'.
           'notsys' Undo the online Tsys correction. Useful if RFI in
                    the tvchannel range has caused the corrections
                    to be very noisy. The resulting data will be in raw
                    counts scaled down by 10^6.
           'nopack' Don't pack the two CABB autocorrelation bins into
                    one bin. The autocorrelation bin 1 and 2 will
                    contain noise cal OFF and ON data.
                    The default is to repack the info into bin 1:
                    XX and YY will contain GTP and SDO data in the real
                    and imaginary part; XY will contain the OFF data and
                    YX will contain the ON-OFF data (for XY). This will
                    allow recalculation of the Tsys and xyphase later.

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.

Key: nopcorr
        This gives the number of frequencies to use per IF for opacity
        correction. The default (2) is to use linear interpolation
        across the spectrum. Maximum value is 32.

Key: edge
        Specify the percentage of edge channels the birdie option will
        flag out. The default is 9.8 which will flag about 100 channels
        from the bottom and top of a 2049 channel spectrum. This
        parameter is only used if the birdie option is specified.
        For concatenated spectra the width of a single zoom is used.
        Note that noise and artefacts go up quickly towards the band
        edge so making this much smaller will not gain you much.
 
Revision: 1.53, 2016/08/25 23:02:21 UTC

Generated by miriad@atnf.csiro.au on 26 Aug 2016