Description

Convert a Miriad visibility dataset into a CASA MeasurementSet

The task importmiriad allows one to import visibilities in the MIRIAD data format to be converted to a MeasurementSet. The task has mainly been tested on data from the ATCA and CARMA telescopes and the inputs are:

#In CASA
#  importmiriad :: Convert a Miriad visibility file into a CASA MeasurementSet
mirfile             =         ''        #  Name of input Miriad visibility file
vis                 =         ''        #  Name of output MeasurementSet
tsys                =      False        #  Use the Tsys to set the visibility
                                        #   weights
spw                 =       [-1]        #  Select spectral windows, default is
                                        #   all
vel                 =         ''        #  Select velocity reference
                                        #   (TOPO,LSRK,LSRD)
linecal             =      False        #  (CARMA) Apply line calibration
wide                =         []        #  (CARMA) Select wide window averages
debug               =          0        #  Display increasingly verbose debug
                                        #   messages
  • The mirfile parameter specifies a single MIRIAD visibility dataset which must have any calibration done in MIRIAD already applied to it. MIRIAD calibration tables are usually applied on the fly within MIRIAD; such steps (e.g., uvaver) need to be taken within MIRIAD such that your MIRIAD visibilities have the calibration permanently applied.
  • Set the tsys parameter to True to change the visibility weights from the MIRIAD default (usually the integration time) to the inverse of the noise variance using the recorded system temperature.
  • The spw parameter can be used to select all or some of the simultaneous spectral windows from the input file. Use the default of ’all’ for all the data or use e.g., spw=’0,2’ to select the first and third window.
  • The vel parameter can be used to set the output velocity frame reference. For ATCA this defaults to ’TOPO’ and for CARMA it defaults to ’LSRK’. Only change this if your data comes out with the incorrect velocity.
  • The linecal parameter is only useful for CARMA data and can apply the line calibration if it is stored with the MIRIAD data.
  • The wide parameter is only useful for CARMA data and can select which of the wide-band channels should be loaded.