Cvel

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: 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