polcal.py

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#
# This file was generated using xslt from its XML file
#
# Copyright 2009, Associated Universities Inc., Washington DC
#
import sys
import os
from  casac import *
import string
from taskinit import casalog
#from taskmanager import tm
import task_polcal
def polcal(vis='', caltable='', field='', spw='', intent='', selectdata=True, timerange='', uvrange='', antenna='', scan='', observation='', msselect='', solint='inf', combine='scan', preavg=300.0, refant='', minblperant=4, minsnr=3.0, poltype='D+QU', smodel=[], append=False, gaintable=[''], gainfield=[''], interp=[''], spwmap=[], gaincurve=False, opacity=[]):

        """Determine instrumental polarization calibrations

      The instrumental polarization factors (D-terms), the calibrator polarization,
      and the R-L polarization angle can be determined using polcal.  The solutions
      can be obtained for each antenna/spwid and even individual channels, if desired.
      Previous calibrations of the total intensity data should be applied on the fly
      when running polcal, since polcal uses the 'data' column, not the 'corrected'
      column.

      After calibrating the gain, bandpass, and (if relevant, for channelized data)
      cross-hand delay, the simplest way to calibrate the polarization data is:

        a) Run polcal with poltype = 'D+QU' on the main 'calibrator' source.  The D terms
           and polarization (QU) of the calibrator will be determined.  Relatively good
           parallactic angle coverage is needed.

        b) If there is little parallactic angle coverage, place the known polarization of
           the main calibrator (or 0) using setjy with the appropriate fluxdensity.  Then
           run polcal with poltype = 'D'.  Run plotcal with xaxis = 'real'; yaxis ='imag'
           to view solutions.  It is best to use an unpolarized calibrator in this 
           instance; large systematic offsets from zero indicate significant source  
           polarization that will bias the polarization calibration.  A mechanism 
           to constrain this bias will be made available in the near future. 

        c) To determine R-L polarization angle, use setjy to put the fluxdensity of the
           polarization calibrator [I,Q,U,0.0] in the model column.  For resolved sources
           put in values associated with an appropriate u-v range.  Polarized models are
           not yet available for the major polarization standard sources, so very
           resolved polarized sources should not be used.

        d) Run polcal with poltype = 'X' and include polarization standard.  Make sure to
           include all previous calibrations, especially the D results.  Run plotxy with
           correlation = 'RL LR' and make sure polarization angles are as expected.

        e) Run applycal with all calibration table, include the D and X tables.  Make sure
           that parang = T

         NOTE: For very high dynamic range, use poltype='Df' or 'Df+QU' to determine 
               D terms for each channel.  Similarly, poltype='Xf' can
               be used to determine a channel-dependent R-L phase
               "bandpass".
         NOTE: Rather than use setjy in b and c above, the new smodel
               parameter may be used in polcal to specify a simple
               point source Stokes model.  

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

      --- 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.
                  Most likely, the main calibrator source should be picked.
              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 
               type 'help par.selection' for more examples.
             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, INCLUSIVE
             spw='*:5~61'; all spw with channels 5 to 62
             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='0:0~10^2,1:20~30^5'; spw 0, channels 0,2,4,6,8,10,
                   spw 1, channels 20,25,30
      intent -- Select observing intent
                default: ''  (no selection by intent)
                intent='*BANDPASS*'  (selects data labelled with
                                      BANDPASS intent)
      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 units meters)
              default: '' (all); example:
              uvrange='0~1000'; uvrange from 0-1000 kilo-lamgda
              uvrange='>4';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 index 5
              antenna='05'; all baselines with antenna name 05, i.e. VLA ant 5
              antenna='5,6,10'; all baselines with antennas 5, 6 and 10
      scan -- Scan number range
      observation -- Observation ID(s).
                     default: '' = all
                     example: '0~2,4'
      msselect -- Optional complex data selection (ignore for now)

      --- Solution parameters
      poltype -- Type of instrumental polarization solution
              'D+QU' (or 'Df+QU')  solve also for apparent source polarization (channelized D)
                 Need relatively good parallactic angle coverage for this
              'D' (or 'Df') solve only for instrumental polarization (channelized).  The
                 I, Q, U flux density of the source can be placed in the model column using
                 setjy.  Use for poor parallactic angle coverage.
              'X' (or 'Xf') = solve only for position angle correction (channelized).  
                 The source must have its I, Q, U flux density in the model column 
                 or specified in smodel.  If the source is resolved, use a limited 
                 uvrange that is appropriate.
              'D+X' (or 'Df+X') = solve also for position angle offset (channelized D) as
                 well as the D-term.  Not normally done.
              default: 'D+QU'
              The solution used the traditional linear approximation.  Non-linearized options
                  will be avaible soon.
      smodel -- Point source Stokes parameters for source model (experimental)
              default: [] (use MODEL_DATA column)
              examples: [1,0,0,0] (I=1, unpolarized)
                        [5.2,0.2,0.3,0.0] (I=5.2, Q=0.2, U=0.3, V=0.0)
      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='1min'; 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
      preavg -- Pre-averaging interval (sec)
              default=300
              Interval to apply parallactic angle.
      refant -- Reference antenna name
              default: '' => refant = '0'
              example: refant='13' (antenna with index 13)
                       refant='VA04' (VLA antenna #4)
                       refant='EA02,EA23,EA13' (EVLA antenna EA02, use
                                EA23 and EA13 as alternates if/when EA02
                                drops out)
              Use 'go listobs' for antenna listing.
              USE SAME REFERENCE ANTENNA AS USED FOR I CALIBRATION.
      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
      minsnr -- Reject solutions below this SNR
              default: 3.0
      append -- Append solutions to the (existing) table
              default: False; overwrite existing table or make new table

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

      gaintable -- Gain calibration table(s) to apply 
               default: '' (none);  BUT I CALIBRATION TABLES SHOULD GENERALLY BE INCLUDED
               examples: gaintable='ngc5921.gcal'
                         gaintable=['ngc5921.ampcal','ngc5921.phcal']
      gainfield -- Select a subset of calibrators from gaintable(s)
               default:'' ==> all sources in table;
               'nearest' ==> nearest (on sky) available field in table
               otherwise, same syntax as field
               example: gainfield='0~3'
                        gainfield=['0~3','4~6'] means use field 0 through 3
                          from first gain file, field 4 through 6 for second.
      interp -- Interpolation type (in time[,freq]) to use for each gaintable.
                When frequency interpolation is relevant (B, Df, Xf),
                separate time-dependent and freq-dependent interp
                types with a comma (freq _after_ the comma).                
                Specifications for frequency are ignored when the
                calibration table has no channel-dependence.
                Time-dependent interp options ending in 'PD' enable a
                "phase delay" correction per spw for non-channel-dependent
                calibration types.
                default: '' --> 'linear,linear' for all gaintable(s)
                example: interp='nearest'   (in time, freq-dep will be
                                             linear, if relevant)
                         interp='linear,cubic'  (linear in time, cubic
                                                 in freq)
                         interp=',spline'  (spline in freq; linear in
                                            time by default)
                         interp=['nearest,spline','linear']  (for multiple gaintables)
                Options: Time: 'nearest', 'linear'
                         Freq: 'nearest', 'linear', 'cubic', 'spline'
      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), per spw
               default: [] (no opacity correction for any spw)
               examples:
                   A global value for all spws:
                     opacity=0.051
                   Different values for spws 0,1,2:
                     opacity=[0.051, 0.055, 0.057]
                   (if more than 3 spws, spw 3 and higher will
                    be assigned the last specified value, or 0.057)
               Typical VLA values are: 5 GHz - 0.013, 8 GHz - 0.013
               15 GHz - 0.016, 23 GHz - 0.051, 43 GHz - 0.07
      async --  Run asynchronously
               default = False; do not run asychronously

        """
        if type(smodel)==float: smodel=[smodel]
        if type(gaintable)==str: gaintable=[gaintable]
        if type(gainfield)==str: gainfield=[gainfield]
        if type(interp)==str: interp=[interp]
        if type(spwmap)==int: spwmap=[spwmap]
        if type(opacity)==float: opacity=[opacity]

#
#    The following is work around to avoid a bug with current python translation
#
        mytmp = {}

        mytmp['vis'] = vis
        mytmp['caltable'] = caltable
        mytmp['field'] = field
        mytmp['spw'] = spw
        mytmp['intent'] = intent
        mytmp['selectdata'] = selectdata
        mytmp['timerange'] = timerange
        mytmp['uvrange'] = uvrange
        mytmp['antenna'] = antenna
        mytmp['scan'] = scan
        mytmp['observation'] = observation
        mytmp['msselect'] = msselect
        mytmp['solint'] = solint
        mytmp['combine'] = combine
        mytmp['preavg'] = preavg
        mytmp['refant'] = refant
        mytmp['minblperant'] = minblperant
        mytmp['minsnr'] = minsnr
        mytmp['poltype'] = poltype
        mytmp['smodel'] = smodel
        mytmp['append'] = append
        mytmp['gaintable'] = gaintable
        mytmp['gainfield'] = gainfield
        mytmp['interp'] = interp
        mytmp['spwmap'] = spwmap
        mytmp['gaincurve'] = gaincurve
        mytmp['opacity'] = opacity
        pathname='file:///'+os.environ.get('CASAPATH').split()[0]+'/share/xml/'
        trec = casac.utils().torecord(pathname+'polcal.xml')

        casalog.origin('polcal')
        if trec.has_key('polcal') and casac.utils().verify(mytmp, trec['polcal']) :
            result = task_polcal.polcal(vis, caltable, field, spw, intent, selectdata, timerange, uvrange, antenna, scan, observation, msselect, solint, combine, preavg, refant, minblperant, minsnr, poltype, smodel, append, gaintable, gainfield, interp, spwmap, gaincurve, opacity)

        else :
          result = False
        return result