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4.4.6 Baseline-based Calibration (blcal)

You can use the blcal task to solve for baseline-dependent (non-closing) errors. WARNING: this is in general a very dangerous thing to do, since baseline-dependent errors once introduced are difficult to remove. You must be sure you have an excellent model for the source (better than the magnitude of the baseline-dependent errors).

The inputs are:

#  blcal :: Calculate a baseline-based calibration solution (gain or bandpass)  
vis                 =         ’’        #  Name of input visibility file  
caltable            =         ’’        #  Name of output gain calibration table  
field               =         ’’        #  Select field using field id(s) or field name(s)  
spw                 =         ’’        #  Select spectral window/channels  
intent              =         ’’        #  Select observing intent  
selectdata          =      False        #  Other data selection parameters  
solint              =      ’inf’        #  Solution interval  
combine             =     ’scan’        #  Data axes which to combine for solve (scan, spw,  
                                        #   and/or field)  
freqdep             =      False        #  Solve for frequency dependent solutions  
calmode             =       ’ap’        #  Type of solution" (’ap’, ’p’, ’a’)  
solnorm             =      False        #  Normalize average solution amplitudes to 1.0  
gaintable           =       [’’]        #  Gain calibration table(s) to apply on the fly  
gainfield           =       [’’]        #  Select a subset of calibrators from gaintable(s)  
interp              =       [’’]        #  Interpolation mode (in time) to use for each gaintable  
spwmap              =         []        #  Spectral windows combinations to form for  
                                        #   gaintables(s)  
gaincurve           =      False        #  Apply internal VLA antenna gain curve correction  
opacity             =         []        #  Opacity correction to apply (nepers), per spw  
parang              =      False        #  Apply parallactic angle correction  
async               =      False        #  If true the taskname must be started using blcal(...)  

The freqdep parameter controls whether blcal solves for “gain” (freqdep=False) or “bandpass” (freqdep=True) style calibration.

Other parameters are the same as in other calibration tasks. These common calibration parameters are described in § 4.4.1.


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