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| Help on gencal task:
| | {{gencal}} |
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| Specify Calibration Values of Various Types
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| The gencal task provides a means of specifying antenna-based
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| calibration values manually. The values are put in designated
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| tables and applied to the data using applycal.
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| Current antenna-based gencal options (caltype) are:
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| 'amp'= amplitude correction
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| 'ph' = phase correction
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| 'sbd'= single-band delay (phase-frequency slope for each spw)
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| 'mbd'= multi-band delay (phase-frequency slope over all spw)
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| 'antpos' = ITRF antenna position corrections
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| 'antposvla' = VLA-centric antenna position corrections
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| The calibration specifications are not time-variable in the
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| present implementation. Calibration values can be assigned to
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| each spw, antenna and pol selection, where applicable. The
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| same caltable can be specified for multipl runs of gencal,
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| in which case the specified parameters will be incorporated
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| cumulatively. E.g., amplitude parameters (caltype='amp')
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| multiply and phase-like parameters ('ph', 'sbd','mbd','antpos')
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| add. 'amp' and 'ph' parameters can be incorporated into the
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| same caltable (in separate runs), but each of the other types
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| require their own unique caltable. A mechanism for
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| specifying manual corrections via a text file will be provided in
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| the future.
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| The caltables are applied to the data by using applycal. Other
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| calibration tables must also be present, if applicable.
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| For antenna position corrections (caltype='antpos'), the antenna
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| position offsets are specified in the ITRF frame. For VLA position
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| corrections in the VLA-centric frame, use caltype='antposvla', and gencal
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| will rotate them to ITRF before storing them in the output caltable.
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| Keyword arguments:
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| vis -- Name of input visibility file
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| default: none. example: vis='ngc5921.ms'
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| caltable -- Name of input/output caltable. If it does not
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| exist, it will be created. Specifying an
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| existing table will result in the parameters
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| being applied cumulatively. Only a single
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| time-stamp for all calibrations are supported,
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| currently. Do not use a caltable
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| created by gaincal, bandpass, etc.
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| default: none. example: caltable='test.G'
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| caltype -- The calibration parameter type being specified.
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| Options include:
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| 'amp' = gain (G) amplitude (1 real parameter per
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| pol, antenna, spw)
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| 'ph' = gain (G) phase (deg) (1 real parameter per
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| pol, antenna, spw)
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| 'sbd' = single-band delays (nsec) (1 real parameter
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| per pol, antenna, spw)
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| 'mbd' = multi-band delay (nsec) (1 real parameter
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| per pol, antenna, spw)
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| 'antpos' = antenna position corrections (m) (3 real
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| ITRF offset parameters per antenna; spw, pol
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| selection will be ignored)
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| 'antposvla' = antenna position corrections (m) specified
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| in the old VLA-centric coordinate system
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| default: none.
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| example: caltype='ph'
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| spw -- Spectral window selection for specified parameters.
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| default: spw='' (specified parameters apply to all spws)
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| example: spw = '2,3,4'
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| antenna -- Antenna selection for specified parameters.
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| default: antenna='' (specified parameters apply to all antennas)
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| example: antenna='EA02, EA03' (specified parameter(s) to
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| apply to EA02 and EA03 only)
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| pol -- Polarization selection for specified parameters.
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| default: pol='' (specified parameters apply to all polarizations)
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| example: pol='R' (specified parameters to apply to
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| R only)
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| parameter -- The calibration parameters, specified as a list, to
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| store in the caltable for the spw, antenna, and pol
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| selection. The required length of the list is
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| determined by the caltype and the spw, antenna, pol
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| selection. One "set" of parameters (e.g., one value
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| for 'amp', 'ph', etc., three values for 'antpos')
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| specified the same value for all indicated spw, antenna,
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| and pol.
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| OR,
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| When specifying a long list of calibration parameter values,
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| these should be ordered first (fastest) by pol (if pol!=''),
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| then by antenna (if antenna!=''), and finally (sloweset) by
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| spw (if spw!=''). Unspecified selection axes must not be
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| enumerated in the parameter list
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|
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| Examples:
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| gencal(vis='test.ms',caltable='test.G',caltype='amp',
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| spw='',antenna='',pol='',
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| parameter=[3])
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| --> Antenna-based gain amplitude corrections for all spws, antennas,
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| and polarizations will be multiplied by 3. When applied
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| to visibility data, this correction will produce a
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| corrected visibility than is (1/3*1/3) less than the
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| uncorrected visibility.
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| gencal(vis='test.ms',caltable='test.G',caltype='ph',
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| spw='',antenna='EA03,EA04',pol='',
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| parameter=[45,120])
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| --> Gain phase corrections for antennas EA03 and EA04
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| will be adjusted (additive) by 45 and 120
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| degrees (respectively), for all spws and polarizations.
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| When these phases are applied to visibility data, the
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| visibility phases will decrease or increase by the
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| specified amount where the selected antennas occur
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| first or second (respectively) in each baseline. E.g.,
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| the phase of baseline EA03-EA04 will change by (-45+120)
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| = + 75 degrees. Baseline EA01-EA03's phase will change
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| by +45 degrees; baseline EA04-EA05's phase will change
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| by -120 degrees. The same phase sign convention is
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| used for delay and antenna position corrections.
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| gencal(vis='test.ms',caltable='test.G',caltype='ph',
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| spw='',antenna='EA05,EA06',pol='R',
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| parameter=[63,-34])
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| --> Gain phase corrections for antennas EA05 and EA06
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| will be adjusted (additive) by 63 and -34
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| degrees (respectively), in R only, for all spws
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| gencal(vis='test.ms',caltable='test.G',caltype='ph',
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| spw='',antenna='EA09,EA10',pol='R,L',
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| parameter=[14,-23,-130,145])
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| --> Gain phase corrections in all spws will be adjusted for
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| antenna EA09 by 14 deg in R and -23 deg in L, and for
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| antenna EA10 by -130 deg in R and 145 deg in L.
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| gencal(vis='test.ms',caltable='test.G',caltype='ph',
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| spw='2,3',antenna='EA09,EA10',pol='',
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| parameter=[14,-23,-130,145])
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| --> Gain phases corrections in both polarizations will be adjusted for
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| antenna EA09 by 14 deg in spw 2 and -23 deg in spw 3, and for
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| antenna EA10 by -130 deg in spw 2 and 145 deg in spw 3.
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| gencal(vis='test.ms',caltable='test.G',caltype='sbd',
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| spw='2,3',antenna='EA09,EA10',pol='',
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| parameter=[14,-23,-130,145])
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| --> Delay corrections in both polarizations will be adjusted for
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| antenna EA09 by 14 nsec in spw 2 and -23 nsec in spw 3, and for
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| antenna EA10 by -130 nsec in spw 2 and 145 nsec in spw
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| 3. See the above example for caltype='ph' for details
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| of the sign convention adopted when applying delay corrections.
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| gencal(vis='test.ms',caltable='test.G',caltype='antpos',
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| antenna='EA09,EA10',
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| parameter=[0.01,0.02,0.03, -0.03,-0.01,-0.02])
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| --> Antenna position corrections in meters (in ITRF) for
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| antenna EA09 (dBx=0.01, dBy=0.02, dBz=0.03) and for
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| antenna EA10 (dBx=-0.03, dBy=-0.01, dBz=-0.02)
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| See the above example for caltype='ph' for details
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| of the sign convention adopted when applying antpos
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| corrections.
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| gencal(vis='test.ms',caltable='test.G',caltype='antposvla',
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| antenna='EA09,EA10',
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| parameter=[0.01,0.02,0.03, -0.03,-0.01,-0.02])
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| --> Antenna position corrections (in the traditional VLA-centric
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| frame) will be introduced in meters for
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| antenna EA09 (dBx=0.01, dBy=0.02, dBz=0.03) and for
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| antenna EA10 (dBx=-0.03, dBy=-0.01, dBz=-0.02)
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| These offsets will be rotated to the ITRF frame before
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| storing them in the caltable.
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| See the above example for caltype='ph' for details
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| of the sign convention adopted when applying antpos
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| corrections.
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