wvrgcal

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0.1.139 wvrgcal

Requires:

Synopsis
Generate a gain table based on Water Vapour Radiometer data

Description

Information about the observation and the performance of WVRGCAL is written to the CASA logger and also returned in a dictionary; see the CASA cookbook for a more detailed description of these parameters. The dictionary element ’success’ is True if no errors occured.

Of particular note is the discrepancy parameter (Disc): high values (¿ a few hundred microns) may indicate some levels of cloud contamination and the effect of applying the WVRGCAL correction should be checked; values ¿ 1000 um in all antennas have currently been found to indicate that WVRGCAL correction should not be used.

vis – Name of input visibility file default: none; example: vis=’ngc5921.ms’

caltable – Name of output gain calibration table default: none; example: caltable=’ngc5921.wvr’

toffset – Time offset (sec) between interferometric and WVR data default: 0 (ALMA default for cycle 1, for cycle 0, i.e. up to Jan 2013 it was -1)

segsource – Do a new coefficient calculation for each source default: True

tie – Prioritise tieing the phase of these sources as well as possible (requires segsource=True) default: [] example: [’3C273,NGC253’, ’IC433,3C279’]

sourceflag – Flag the WVR data for these source(s) as bad and do not produce corrections for it (requires segsource=True) default: [] (none) example: [’3C273’]

nsol – Number of solutions for phase correction coefficients during this observation. By default only one set of coefficients is generated for the entire observation. If more sets are requested, then they will be evenly distributed in time throughout the observation. Values ¿ 1 require segsource=False. default: 1

disperse – Apply correction for dispersion default: False

wvrflag – Regard the WVR data for these antenna(s) as bad and use interpolated values instead default: [] (none) example: [’DV03’,’DA05’,’PM02’]

statfield – Compute the statistics (Phase RMS, Disc) on this field only default: ” (all)

statsource – Compute the statistics (Phase RMS, Disc) on this source only default: ” (all)

smooth – Smooth the calibration solution on the given timescale default: ” (no smoothing), example: ’3s’ smooth on a timescale of 3 seconds

scale – Scale the entire phase correction by this factor default: 1. (no scaling)

spw – List of the spectral window IDs for which solutions should be saved into the caltable default: [] (all spectral windows), example [17,19,21,23]

wvrspw – List of the spectral window IDs from which the WVR data should be taken default: [] (all WVR spectral windows), example [0]

reversespw – Reverse the sign of the correction for the listed SPWs (only neede for early ALMA data before Cycle 0) default: ” (none), example: reversespw=’0~2,4’; spectral windows 0,1,2,4

cont – Estimate the continuum (e.g., due to clouds) default: False

maxdistm – maximum distance (m) an antenna may have to be considered for being part of the antenna set (minnumants to 3 antennas) for the interpolation of a solution for a flagged antenna default: 500.

minnumants – minimum number of near antennas required for interpolation default: 2

mingoodfrac – If the fraction of unflagged data for an antenna is below this value (0. to 1.), the antenna is flagged. default: 0.8

usefieldtab – derive the antenna AZ/EL values from the FIELD rather than the POINTING table default: False

refant – use the WVR data from this antenna for calculating the dT/dL parameters (can give ranked list) default: ” (use the first good or interpolatable antenna), examples: ’DA45’ - use DA45 [’DA45’,’DV51’] - use DA45 and if that is not good, use DV51 instead

offsetstable – (experimental) subtract the temperature offsets in this table from the WVR measurements before using them to calculate the phase corrections default: ” (do not apply any offsets) examples: ’uid___A002_Xabd867_X2277.cloud_offsets’ use the given table

Arguments


Inputs
vis	Name of input visibility file
	allowed:	string
	Default:
caltable	Name of output gain calibration table
	allowed:	string
	Default:
toffset	Time offset (sec) between interferometric and WVR data
	allowed:	double
	Default:	0
segsource	Do a new coefficient calculation for each source
	allowed:	bool
	Default:	True
sourceflag	Regard the WVR data for these source(s) as bad and do not produce corrections for it (requires segsource=True)
	allowed:	stringArray
	Default:
tie	Prioritise tieing the phase of these sources as well as possible (requires segsource=True)
	allowed:	stringArray
	Default:
nsol	Number of solutions for phase correction coefficients (nsol>1 requires segsource=False)
	allowed:	int
	Default:	1
disperse	Apply correction for dispersion
	allowed:	bool
	Default:	False
wvrflag	Regard the WVR data for these antenna(s) as bad and replace its data with interpolated values from neighbouring antennas
	allowed:	stringArray
	Default:
statfield	Compute the statistics (Phase RMS, Disc) on this field only
	allowed:	string
	Default:
statsource	Compute the statistics (Phase RMS, Disc) on this source only
	allowed:	string
	Default:
smooth	Smooth calibration solution on the given timescale
	allowed:	string
	Default:
scale	Scale the entire phase correction by this factor
	allowed:	double
	Default:	1.
spw	List of the spectral window IDs for which solutions should be saved into the caltable
	allowed:	intArray
	Default:
wvrspw	List of the spectral window IDs from which the WVR data should be taken
	allowed:	intArray
	Default:
reversespw	Reverse the sign of the correction for the listed SPWs (only needed for early ALMA data before Cycle 0)
	allowed:	string
	Default:
cont	Estimate the continuum (e.g., due to clouds) (experimental)
	allowed:	bool
	Default:	False
maxdistm	maximum distance (m) of an antenna used for interpolation for a flagged antenna
	allowed:	double
	Default:	500.
minnumants	minimum number of near antennas (up to 3) required for interpolation
	allowed:	int
	Default:	2
mingoodfrac	If the fraction of unflagged data for an antenna is below this value (0. to 1.), the antenna is flagged.
	allowed:	double
	Default:	0.8
usefieldtab	derive the antenna AZ/EL values from the FIELD rather than the POINTING table
	allowed:	bool
	Default:	False
refant	use the WVR data from this antenna for calculating the dT/dL parameters (can give ranked list)
	allowed:	stringArray
	Default:
offsetstable	(experimental) subtract the temperature offsets in this table from the WVR measurements before calculating the phase corrections
	allowed:	string
	Default:

Returns
variant

Example

wvrgcal(vis=’uid___A002_X1d54a1_X5.ms’, caltable=’cal-wvr-uid___A002_X1d54a1_X5.W’,
toffset=-1, segsource=True, tie=[’Titan,1037-295,NGC3256’], statsource=’1037-295’)

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