Accum

Help on accum task:

Accumulate incremental calibration solutions into a calibration table

       Accum will interpolate and extrapolate a temporal calibration
       table onto a new table that has a regularly-space time grid.

       The first run of accum defines the time grid and fills this
       table with the results from the input table.

       Subsequent use of accum will combine additional calibration
       tables onto the same grid of the initial accum table to obtain
       an output accum table.  See below for a concrete example.


     Keyword arguments:

     vis -- Name of input visibility file
             default: none.  example: vis='ngc5921.ms'
     tablein -- Input cumulative calibration table.
             default: ''  means none
             On first execution of accum, tablein=''
             and accumtime is used to generate tablein with
             the specified time gridding.
     accumtime -- The time separation when making tablein.
             default: 1.0  (1 second).  This time should not be
             less than the visibiility sampling time, but should
             be less than about 30% of a typical scan length.
     incrtable -- The calibration data to be interpolated onto the
             tablein file.
             default: ''.  Must be specified
     caltable -- The output cumulated calibration file.
             default: ''  means use tablein as the output file
             
     field -- Select field(s) from tablein to process.
              ['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
     calfield -- Select field(s) from incrtable to process.
            default: '' = all fields
     interp -- Interpolation mode (in time) to use for each gaintable
            default: '' --> 'linear' for all gaintable(s)
            example: interp='nearest'
                     interp=['nearest','linear']  (for multiple gaintables)
            Options: 'nearest', 'linear', 'aipslin'
     spwmap -- Spectral windows combinations to form for gaintable(s)
            default: [] (apply solutions from each spw to that spw only)
            Example:  spwmap=[0,0,1,1] means apply the caltable solutions
                      from spw = 0 to the spw 0,1 and spw 1 to spw 2,3.
                      spwmap=[[0,0,1,1],[0,1,0,1]]  (for multiple gaintables)
     async -- Run task in a separate process 
             default: False; example: async=True

     Examples:

       Create an accum table with 10-sec sampling, filling it with the calibration
          in 'first_cal' with the desired interpolation.

           taskname = 'accum'
             default()
             vis = 'mydata.ms'
             tablein = ''
             accumtime = 10
             incrtable = 'first_cal'
             caltable = 'accum1_cal'
             accum()

       If you plot 'accum1_cal' with plotcal, you can see how the incrtable was
             interpolated.

       Continue accumulating calibrations in accum1_cal from 'second_cal'

           taskname = 'accum'
             default()
             vis = 'mydata.ms'
             tablein = 'accum1_cal'
             incrtable = 'second_cal'
             caltable = 'accum1_cal'
             accum()

       Incorporate gaincurve, opacity, parang once and for all

          taskname= 'gaincal'
             vis = 'mydata.ms'
             caltable = 'first_cal'
               etc
             gaincurve = T
             opacity = 0.11
             parang = T
             gaincal()

             tablein = ''
             accumtime = 10
             incrtable = 'first_cal'
             caltable = 'accum1_cal'
             accum()

       If you plot 'accum1_cal' with plotcal, you can see how the incrtable was
             interpolated.

       Continue accumulating calibrations in accum1_cal from 'second_cal'

           taskname = 'accum'
             default()
             vis = 'mydata.ms'
             tablein = 'accum1_cal'
             incrtable = 'second_cal'
             caltable = 'accum1_cal'
             accum()

       Incorporate gaincurve, opacity, parang once and for all

          taskname= 'gaincal'
             vis = 'mydata.ms'
             caltable = 'first_cal'
               etc
             gaincurve = T
             opacity = 0.11
             parang = T
             gaincal()

           taskname = 'accum'
             default()
             vis = 'mydata.ms'
             tablein = ''
             accumtime = 10
             incrtable = 'first_cal'
             caltable = 'accum1_cal'
             accum()

         accum1_cal with contain not only the gaincal solution, but the gaincurve,
             opacity and parang correction.  Hence, when applying accum1_cal
             on the fly for subsequent calibrations (gaincal, bandpass) or applying
             the calibrations, then
                gaincurve=F; opacity = 0.0; parang = F  should be used