Data Selection

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2.3 Data Selection

Once in MS form, subsets of the data can be operated on using the tasks and tools. In CASA, there are three common data selection parameters used in the various tasks: field, spw, and selectdata. In addition, the selectdata parameter, if set to True, will open up a number of other sub-parameters for selection. The selection operation is unified across all the tasks. The available selectdata parameters may not be the same in all tasks. But if present, the same parameters mean the same thing and behave in the same manner when used in any task.

For example:

field               =         ’’        #   field names or index of calibrators ’’==>all
spw                 =         ’’        #   spectral window:channels: ’’==>all
selectdata          =      False        #   Other data selection parameters

versus

field               =         ’’        #   field names or index of calibrators ’’==>all
spw                 =         ’’        #   spectral window:channels: ’’==>all
selectdata          =       True        #   Other data selection parameters
     timerange      =         ’’        #   time range: ’’==>all
     uvrange        =         ’’        #   uv range’’=all
     antenna        =         ’’        #   antenna/baselines: ’’==>all
     scan           =         ’’        #   scan numbers: Not yet implemented
     msselect       =         ’’        #   Optional data selection (Specialized. but see help)

The following are the general syntax rules and descriptions of the individual selection parameters of particular interest for the tasks:

  2.3.1 General selection syntax
   2.3.1.1 String Matching
  2.3.2 The field Parameter
  2.3.3 The spw Parameter
   2.3.3.1 Channel selection in the spw parameter
  2.3.4 The selectdata Parameters
   2.3.4.1 The antenna Parameter
   2.3.4.2 The scan Parameter
   2.3.4.3 The timerange Parameter
   2.3.4.4 The uvrange Parameter
   2.3.4.5 The observation Parameter
   2.3.4.6 The msselect Parameter

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