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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== Help for bandpass: ==
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{{bandpass}}
 
 
<pre>
 
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
 
</pre>
 

Latest revision as of 19:24, 6 May 2015