Difference between revisions of "Blcal"

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Revision as of 16:43, 16 March 2012

Help on blcal task:

Calculate a baseline-based calibration solution (gain or bandpass)

        This task determines a baseline by baseline gain (time) or bandpass (freq)
        for all baseline pairs in the data set.   For the usual antenna-based calibration
        of interferometric data, this task gaincal is recommended, even with only one
        to three baselines.  For arrays with closure errors, use blcal

        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.gcal'

       --- 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
               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 units kilo-lambda)
               default: '' (all); example:
               uvrange='0~1000kl'; uvrange from 0-1000 kilo-lamgda
               uvrange='>4kl';uvranges greater than 4 kilo lambda
               uvrange='0~1000km'; uvrange in kilometers
        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 and 6
        scan -- Scan number range - New, under developement
        msselect -- Optional complex data selection (ignore for now)

        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
        freqdep -- Solve for frequency dependent solutions
               default: False (gain; True=bandpass); example: freqdep=True
        calmode -- Type of solution
               default: 'ap' (amp and phase); example: calmode='p'
               Options: 'p','a','ap'
        solnorm -- Normalize solutions.  For freqdep=F, this is a global (per-spw) 
                   normalization of amplitudes (only).  For freqdep=T, each baseline 
                   solution spectrum is separately normalized by its (complex) mean.
                default: False (no normalization)

        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'
                        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
        freqdep -- Solve for frequency dependent solutions
               default: False (gain; True=bandpass); example: freqdep=True
        calmode -- Type of solution
               default: 'ap' (amp and phase); example: calmode='p'
               Options: 'p','a','ap'
        solnorm -- Normalize solutions.  For freqdep=F, this is a global (per-spw) 
                   normalization of amplitudes (only).  For freqdep=T, each baseline 
                   solution spectrum is separately normalized by its (complex) mean.
                default: False (no normalization)

        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