Content-type: text/html Manpage of atlod


Section: User Commands (1)
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atlod - Convert an RPFITS file into Miriad uv format.  




data transfer  


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


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.
Name of the output Miriad uv data-set. No default.
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.
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
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
  '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.  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
  '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
  '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
  '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.
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
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.
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.

lod.for,v 1.17 2011/02/11 12:54:31 pteuben Exp $




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Time: 18:35:38 GMT, July 05, 2011