Difference between revisions of "Bandpass"

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(Created page with '== Help for bandpass: == <pre> Calculates a bandpass calibration solution Determines the amplitude and phase as a function of frequency for each spectral window c…')
 
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Revision as of 16:43, 16 March 2012

Help for bandpass:

Calculates a bandpass calibration solution

       Determines the amplitude and phase as a function of frequency for
       each spectral window containing more than one channel.  Strong sources
       (or many observations of moderately strong sources) are needed to obtain
       accurate bandpass functions.  The two solution choices are: Individual
       antenna/based channel solutions 'B'; and a polynomial fit over the channels
       'BPOLY'.  The 'B' solutions can determined at any specified time interval, and
       is recommended if each channel has good signal-to-noise.  Other, 'BPOLY' is
       recommended.

      Keyword arguments:
      vis -- Name of input visibility file
              default: none; example: vis='ngc5921.ms'
      caltable -- Name of output bandpass calibration table
              default: none; example: caltable='ngc5921.bcal'

      --- Data Selection (see help par.selectdata for more detailed information)

      field -- Select field using field id(s) or field name(s).
                 [run listobs to obtain the list id's or names]
              default: ''=all fields
              If field string is a non-negative integer, it is assumed a field index
                otherwise, it is assumed 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 adn 3C295
              field = '3,4C*'; field id 3, all names starting with 4C
      spw -- Select spectral window/channels
              default: ''=all spectral windows and channels
              spw='0~2,4'; spectral windows 0,1,2,4 (all channels)
              spw='<2';  spectral windows less than 2 (i.e. 0,1)
              spw='0:5~61'; spw 0, channels 5 to 61
              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
                        NOTE: ';' to separate channel selections
              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
      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 dat 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' data within one integration of time
              timerange='>10:24:00' data after this time
      uvrange -- Select data within uvrange (default meters)
              default: '' (all); example:
              uvrange='0~1000kl'; uvrange from 0-1000 kilo-lamgda
              uvrange='>4kl';uvranges greater than 4 kilo-lambda
      antenna -- Select data based on antenna/baseline
              default: '' (all)
              If antenna string is a non-negative integer, it is assumed an antenna index
                otherwise, it is assumed as 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'; baseline 5-6 and 7-8
              antenna='5'; all baselines with antenna 5
              antenna='5,6,10'; all baselines with antennas 5, 6 and 10
       scan -- Select data based on scan number - New, under developement
               default: '' (all); example: scan='>3'
       msselect -- Optional complex data selection (ignore for now)

       --- Solution parameters
       solint --  Solution interval (units optional) 
              default: 'inf' (~infinite, up to boundaries controlled by combine); 
              Options: 'inf' (~infinite), 'int' (per integration), any float
                       or integer value with or without units
              examples: solint='1m'; solint='60s', solint=60 --> 1 minute
                        solint='0s'; solint=0; solint='int' --> per integration
                        solint-'-1s'; solint='inf' --> ~infinite, up to boundaries
                        enforced by combine
       combine -- Data axes to combine for solving
              default: 'scan' --> solutions will break at field and spw boundaries,
                        but may extend over multiple scans (per field and spw) up
                        to solint.
              Options: '','scan','spw',field', or any comma-separated combination
              example: combine='scan,spw'  --> extend solutions over scan boundaries
                       (up to the solint), and combine spws for solving
       refant -- Reference antenna name (string)
               default: '' (no reference antenna)
                example: refant='13' (antenna with index 13)
                       refant='VA04' (VLA antenna #4)
               Use 'go listobs' for antenna listing
       minblperant -- Minimum number of baselines required per antenna for each solve
                    Antennas with fewer baaselines are excluded from solutions. Amplitude
                    solutions with fewer than 4 baselines, and phase solutions with fewer 
                    than 3 baselines are only trivially constrained, and are no better
                    than baseline-based solutions.
                    default: 4
                    example: minblperant=10  => Antennas participating on 10 or more 
                             baselines are included in the solve
       solnorm -- Normalize bandpass amplitudes and phase for each
               spw, pol, ant, and timestamp
               default: False (no normalization)
       bandtype -- Type of bandpass solution (B or BPOLY)
               default: 'B'; example: bandtype='BPOLY'
               'B' does a channel by channel solution for each
                   specified spw.
               'BPOLY' is somewhat experimental. It will fit an
                   nth order polynomial for the amplitude and phase
                   as a function of frequency. Only one fit is made
                   for all specified spw, and edge channels should be
                   omitted.
                Use taskname=plotcal in order to compare the results from
                   B and BPOLY.
       fillgaps -- Fill flagged solution channels by interpolation
               default: 0 (don't interpolate)
               example: fillgaps=3 (interpolate gaps 3 channels wide and narrower)
       degamp -- Polynomial degree for BPOLY amplitude solution
               default: 3; example: degamp=2
       degphase -- Polynomial degree for BPOLY phase solution
               default: 3; example: degphase=2
       visnorm -- Normalize data prior to BPOLY solution
               default: False; example: visnorm=True
       maskcenter -- Number of channels to avoid in center of each band
               default: 0; example: maskcenter=5 (BPOLY only)
       maskedge -- Fraction of channels to avoid at each band edge (in %)
               default: 5; example: maskedge=3 (BPOLY only)
       append -- Append solutions to the (existing) table
               default: False; example: append=True

      --- Other calibrations to apply on the fly before determining bandpass solution

      gaintable -- Gain calibration table(s) to apply 
               default: '' (none);
               examples: gaintable='ngc5921.gcal'
                         gaintable=['ngc5921.ampcal','ngc5921.phcal']
      gainfield -- Select a subset of calibrators from gaintable(s)
               default:'' ==> all sources in table;
               same syntax as field
               example: gainfield='0~3'
                        gainfield=['0~3','4~6']
      interp -- Interpolation mode (in time) to use for each gaintable
                default: '' --> 'linear' for all gaintable(s)
                example: interp='nearest'
                         interp=['nearest','linear']
                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]]
       append -- Append solutions to the (existing) table
               default: False; example: append=True

      --- Other calibrations to apply on the fly before determining bandpass solution

      gaintable -- Gain calibration table(s) to apply 
               default: '' (none);
               examples: gaintable='ngc5921.gcal'
                         gaintable=['ngc5921.ampcal','ngc5921.phcal']
      gainfield -- Select a subset of calibrators from gaintable(s)
               default:'' ==> all sources in table;
               same syntax as field
               example: gainfield='0~3'
                        gainfield=['0~3','4~6']
      interp -- Interpolation mode (in time) to use for each gaintable
                default: '' --> 'linear' for all gaintable(s)
                example: interp='nearest'
                         interp=['nearest','linear']
                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]]
      gaincurve -- Apply internal VLA antenna gain curve correction  (True/False)
               default: False; 
               Use gaincurve=True ONLY for VLA data
      opacity -- Opacity correction to apply (nepers)
               default: 0.0 (no opacity correction)
               example: opacity=0.051
               Typical VLA values are: 5 GHz - 0.013, 8 GHz - 0.013
               15 GHz - 0.016, 23 GHz - 0.051, 43 GHz - 0.07
      parang -- If True, apply the parallactic angle correction (required
               for polarization calibration)
               default: False