gencal – Specify Calibration Values of Various Types – calibration task

Description

The gencal task provides a means of specifying antenna-based calibration values manually. The values are put in designated tables and applied to the data using applycal. Several specialized calibrations are also generated with gencal.

Current antenna-based gencal options (caltype) are: * ‘amp’= amplitude correction * ‘ph’ = phase correction * ‘sbd’= single-band delay (phase-frequency slope for each spw) * ‘mbd’= multi-band delay (phase-frequency slope over all spw) * ‘antpos’ = ITRF antenna position corrections * ‘antposvla’ = VLA-centric antenna position corrections * ‘tsys’ = Tsys from the SYSCAL table (ALMA) * ‘swpow’ = EVLA switched-power gains (experimental) * ‘evlagain’ (=’swpow’) (this syntax will deprecate) * ‘rq’ = EVLA requantizer gains _only_ * ‘swp/rq’ = EVLA switched-power gains divided by requantizer gain * ‘opac’ = Tropospheric opacity * ‘gc’ = Gain curve (zenith-angle-dependent gain) (VLA only) * ‘eff’ = Antenna efficiency (sqrt(K/Jy)) (VLA only) * ‘gceff’ = Gain curve and efficiency (VLA only) * ‘tecim’ = Time-dep TEC image specified in infile

Parameters

Title

Parameter

Default

Description

vis

''

Name of input visibility file

caltable

''

Name of input calibration table

caltype

''

The calibration type: (amp, ph, sbd, mbd, antpos, antposvla, tsys, evlagain, opac, gc, gceff, eff, tecim)

infile

''

Input ancilliary file

spw

''

Select spectral window/channels

antenna

''

Select data based on antenna/baseline

pol

''

Calibration polarizations(s) selection

parameter

numpy.array( [  ] )

The calibration values

uniform

True

Assume uniform calibration values across the array

Parameter Explanations

vis

''

Name of input visibility file

Default: none

Example: vis=’ngc5921.ms’

caltable

''

Name of input calibration table

Default: none

If a calibration table does not exist, it will be created. Specifying an existing table will result in the parameters being applied cumulatively. Only a single time-stamp for all calibrations are supported, currently. Do not use a caltable created by gaincal, bandpass, etc.

Example: caltable=’test.G’

caltype

''

The calibration parameter type being specified

Default: none Options: ‘amp’, ‘ph’, ‘sbd’, ‘mbd’, ‘antpos’, ‘antposvla’, ‘tsys’, ‘evlagain’, ‘opac’, ‘gc’, ‘gceff’, ‘eff’, ‘tecim’

  • ‘amp’ = gain (G) amplitude (1 real parameter per pol, antenna, spw)

  • ‘ph’ = gain (G) phase (deg) (1 real parameter per pol, antenna, spw)

  • ‘sbd’ = single-band delays (nsec) (1 real parameter per pol, antenna, spw)

  • ‘mbd’ = multi-band delay (nsec) (1 real parameter per pol, antenna, spw)

  • ‘antpos’ = antenna position corrections (m) (3 real ITRF offset parameters per antenna; spw, pol selection will be ignored) With antenna=’’, this triggers an automated lookup of antenna positions for EVLA and ALMA.

  • ‘antposvla’ = antenna position corrections (m) specified in the old VLA-centric coordinate system

  • ‘tsys’ = Tsys from the SYSCAL table (ALMA)

  • ‘evlagain’ = EVLA switched-power gains (experimental)

  • ‘opac’ = Tropospheric opacity (1 real parameter per antenna, spw)

  • ‘gc’ = Antenna zenith-angle dependent gain curve (auto-lookup)

  • ‘gceff’ = Gain curve and efficiency (auto-lookup)

  • ‘eff’ = Antenna efficiency (auto-lookup)

    Example: caltype=’ph’

infile

''

Input ancilliary file

Subparameter of caltype=’gc|gceff|tecim’ Default: none

spw

''

Select spectral window/channels

Default: ‘’ (all spectral windows and channels)

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 spw=’0,10,3:3~45’; spw 0,10 all channels, spw 3 - chans 3 to 45. spw=’0~2:2~6’; spw 0,1,2 with channels 2 through 6 in each. spw = ‘*:3~64’ channels 3 through 64 for all sp id’s spw = ‘ :3~64’ will NOT work.

antenna

''

Select data based on antenna/baseline

Subparameter of selectdata=True Default: ‘’ (all)

If antenna string is a non-negative integer, it is assumed an antenna index, otherwise, it is assumed as an antenna name

Examples: 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’; baselines with indices 5-6 and 7-8 antenna=’5’; all baselines with antenna index 5 antenna=’05’; all baselines with antenna number 05 (VLA old name) antenna=’5,6,10’; all baselines with antennas 5,6,10 index numbers

pol

''

Polarization selection for specified parameters

Default: pol=’’ (specified parameters apply to all polarizations)

Example: pol=’R’ (specified parameters to apply to R only)

parameter

numpy.array( [  ] )

The calibration values

The calibration parameters, specified as a list, to store in the caltable for the spw, antenna, and pol selection. The required length of the list is determined by the caltype and the spw, antenna, pol selection. One “set” of parameters (e.g., one value for ‘amp’, ‘ph’, etc., three values for ‘antpos’) specified the same value for all indicated spw, antenna, and pol. OR, When specifying a long list of calibration parameter values, these should be ordered first (fastest) by pol (if pol!=’’), then by antenna (if antenna!=’’), and finally (sloweset) by spw (if spw!=’’). Unspecified selection axes must not be enumerated in the parameter list

uniform

True

Assume uniform calibration values across the array
Subparameter of caltype=’tsys’

Default: True Options: True|False