Difference between revisions of "Cvel"

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(Created page with '== Help on cvel task: == regrid an MS to a new spectral window / channel structure or frame vis -- Name of input visibility file default: none; example: v…')
 
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== Help on cvel task: ==
+
{{cvel}}
 
 
regrid an MS to a new spectral window / channel structure or frame
 
 
 
      vis -- Name of input visibility file
 
              default: none; example: vis='ngc5921.ms'
 
 
 
      outputvis -- Name of output measurement set (required)
 
              default: none; example: vis='ngc5921-regridded.ms'
 
 
 
      passall --  if False, data not meeting the selection is omitted/deleted
 
              or flagged (if in-row); if True, data not meeting the selection
 
              on field and spw is passed through without modification
 
              default: False; example:
 
              field='NGC5921'
 
              passall=False : only data from NGC5921 is included in output MS,
 
                        no data from other fields (e.g. 1331+305) is included
 
              passall=True : data from NGC5921 is transformed by cvel, all other
 
                        fields are passed through unchanged
 
 
 
      field -- Select fields in mosaic.  Use field id(s) or field name(s).
 
                  ['go listobs' to obtain the list id's or names]
 
              default: ''= all fields
 
              If field string is a non-negative integer, it is assumed to
 
                  be a field index otherwise, it is assumed to be a
 
                  field name
 
              field='0~2'; field ids 0,1,2
 
              field='0,4,5~7'; field ids 0,4,5,6,7
 
              field='3C286,3C295'; field named 3C286 and 3C295
 
              field = '3,4C*'; field id 3, all names starting with 4C
 
 
 
      spw --Select spectral window/channels
 
              NOTE: This selects the data passed as the INPUT to mode
 
              default: ''=all spectral windows and channels
 
                spw='0~2,4'; spectral windows 0,1,2,4 (all channels)
 
                spw='0:5~61'; spw 0, channels 5 to 61
 
                spw='<2';  spectral windows less than 2 (i.e. 0,1)
 
                spw='0,10,3:3~45'; spw 0,10 all channels, spw 3,
 
                                  channels 3 to 45.
 
                spw='0~2:2~6'; spw 0,1,2 with channels 2 through 6 in each.
 
                spw='0:0~10;15~60'; spectral window 0 with channels
 
                                    0-10,15-60
 
                spw='0:0~10,1:20~30,2:1;2;3'; spw 0, channels 0-10,
 
                      spw 1, channels 20-30, and spw 2, channels, 1,2 and 3
 
 
 
      selectdata -- Other data selection parameters
 
              default: True
 
 
 
  >>> selectdata=True expandable parameters
 
 
 
              antenna -- Select data based on antenna/baseline
 
                  default: '' (all)
 
                  If antenna string is a non-negative integer, it is
 
                    assumed to be an antenna index, otherwise, it is
 
                    considered an antenna name.
 
                  antenna='5&6'; baseline between antenna index 5 and
 
                                index 6.
 
                  antenna='VA05&VA06'; baseline between VLA antenna 5
 
                                      and 6.
 
                  antenna='5&6;7&8'; baselines 5-6 and 7-8
 
                  antenna='5'; all baselines with antenna index 5
 
                  antenna='05'; all baselines with antenna number 05
 
                                (VLA old name)
 
                  antenna='5,6,9'; all baselines with antennas 5,6,9
 
                                  index numbers
 
 
 
              timerange  -- Select data based on time range:
 
                default = '' (all); examples,
 
                  timerange = 'YYYY/MM/DD/hh:mm:ss~YYYY/MM/DD/hh:mm:ss'
 
                  Note: if YYYY/MM/DD is missing date defaults to first
 
                        day in data set
 
                  timerange='09:14:0~09:54:0' picks 40 min on first day
 
                  timerange= '25:00:00~27:30:00' picks 1 hr to 3 hr
 
                            30min on NEXT day
 
                  timerange='09:44:00' pick data within one integration
 
                            of time
 
                  timerange='>10:24:00' data after this time
 
 
 
              scan -- Scan number range.
 
                  default: '' (all)
 
                  example: scan='1~5'
 
                  Check 'go listobs' to insure the scan numbers are in
 
                        order.
 
 
 
              array -- Select data by (sub)array indices
 
                  default: '' (all); example:
 
                  array='0~2'; arrays 0 to 2
 
 
 
      mode -- Frequency Specification:
 
              NOTE: See examples below:
 
              default: 'channel'
 
                mode = 'channel'; Use with nchan, start, width to specify
 
                        output spw. Produces equidistant grid based on first
 
                        selected channel. See examples below.
 
                mode = 'velocity', means channels are specified in
 
                      velocity.
 
                mode = 'frequency', means channels are specified in
 
                      frequency.
 
                mode = 'channel_b', alternative 'channel' mode.
 
                        Does not force an equidistant grid. Faster.
 
 
 
  >>> mode expandable parameters
 
              Start, width are given in units of channels, frequency
 
                  or velocity as indicated by mode
 
              nchan -- Number of channels in output spw
 
                default: -1 = all channels; example: nchan=3
 
              start -- Start input channel (relative-0)
 
                default=0; example: start=5
 
              width -- Output channel width in units of the input
 
                    channel width (>1 indicates channel averaging)
 
                default=1; example: width=4
 
              interpolation -- Interpolation method
 
                default = 'linear'
 
          examples:
 
              spw = '0,1'; mode = 'channel'
 
                  will produce a single spw containing all channels in spw
 
                      0 and 1
 
              spw='0:5~28^2'; mode = 'channel'
 
                  will produce a single spw made with channels
 
                      (5,7,9,...,25,27)
 
              spw = '0'; mode = 'channel': nchan=3; start=5; width=4
 
                  will produce an spw with 3 output channels
 
                  new channel 1 contains data from channels (5+6+7+8)
 
                  new channel 2 contains data from channels (9+10+11+12)
 
                  new channel 3 contains data from channels (13+14+15+16)
 
              spw = '0:0~63^3'; mode='channel'; nchan=21; start = 0;
 
                      0 and 1
 
              spw='0:5~28^2'; mode = 'channel'
 
                  will produce a single spw made with channels
 
                      (5,7,9,...,25,27)
 
              spw = '0'; mode = 'channel': nchan=3; start=5; width=4
 
                  will produce an spw with 3 output channels
 
                  new channel 1 contains data from channels (5+6+7+8)
 
                  new channel 2 contains data from channels (9+10+11+12)
 
                  new channel 3 contains data from channels (13+14+15+16)
 
              spw = '0:0~63^3'; mode='channel'; nchan=21; start = 0;
 
                  width = 1
 
                  will produce an spw with 21 channels
 
                  new channel 1 contains data from channel 0
 
                  new channel 2 contains data from channel 2
 
                  new channel 21 contains data from channel 61
 
              spw = '0:0~40^2'; mode = 'channel'; nchan = 3; start =
 
                  5; width = 4
 
                  will produce an spw with three output channels
 
                  new channel 1 contains channels (5,7)
 
                  new channel 2 contains channels (13,15)
 
                  new channel 3 contains channels (21,23)
 
 
 
      phasecenter -- direction measure  or fieldid for the mosaic center
 
              default: '' => first field selected ; example: phasecenter=6
 
              or phasecenter='J2000 19h30m00 -40d00m00'
 
 
 
      restfreq -- Specify rest frequency to use for output image
 
              default='' Occasionally it is necessary to set this (for
 
              example some VLA spectral line data).  For example for
 
              NH_3 (1,1) put restfreq='23.694496GHz'
 
 
 
      outframe -- output reference frame
 
              default='' (keep original reference frame) ; example: outframe='bary'
 
 
 
      veltype -- definition of velocity (in mode)
 
              default = 'radio'
 
 
 
      hanning -- if true, Hanning smooth frequency channel data to remove Gibbs ringing
 

Latest revision as of 19:22, 6 May 2015