# wvrgcal¶

wvrgcal(vis, caltable='', toffset=0, segsource=True, sourceflag='', tie='', nsol=1, disperse=False, wvrflag='', statfield='', statsource='', smooth='', scale=1.0, spw='', wvrspw='', reversespw='', cont=False, maxdistm=500.0, minnumants=2, mingoodfrac=0.8, usefieldtab=False, refant='', offsetstable='')[source]

Generate a gain table based on Water Vapour Radiometer data

[Description] [Examples] [Development] [Details]

Parameters
• vis (path) - Name of input visibility file

• caltable (path=’’) - Name of output gain calibration table

• toffset (double=0) - Time offset (sec) between interferometric and WVR data

• segsource (bool=True) - Do a new coefficient calculation for each source

segsource = True
• tie (stringVec=’’) - Prioritise tieing the phase of these sources as well as possible (requires segsource=True)

• sourceflag (stringVec=’’) - Regard the WVR data for these source(s) as bad and do not produce corrections for it (requires segsource=True)

segsource = False
• nsol (int=1) - Number of solutions for phase correction coefficients (nsol>1 requires segsource=False)

• disperse (bool=False) - Apply correction for dispersion

• wvrflag (stringVec=’’) - Regard the WVR data for these antenna(s) as bad and replace its data with interpolated values from neighbouring antennas

• statfield (string=’’) - Compute the statistics (Phase RMS, Disc) on this field only

• statsource (string=’’) - Compute the statistics (Phase RMS, Disc) on this source only

• smooth (string=’’) - Smooth calibration solution on the given timescale

• scale (double=1.) - Scale the entire phase correction by this factor

• spw (intVec=’’) - List of the spectral window IDs for which solutions should be saved into the caltable

• wvrspw (intVec=’’) - List of the spectral window IDs from which the WVR data should be taken

• reversespw (string=’’) - Reverse the sign of the correction for the listed SPWs (only needed for early ALMA data before Cycle 0)

• cont (bool=False) - Estimate the continuum (e.g., due to clouds) (experimental)

• maxdistm (double=500.) - maximum distance (m) of an antenna used for interpolation for a flagged antenna

• minnumants (int=2) - minimum number of near antennas (up to 3) required for interpolation

• mingoodfrac (double=0.8) - If the fraction of unflagged data for an antenna is below this value (0. to 1.), the antenna is flagged.

• usefieldtab (bool=False) - derive the antenna AZ/EL values from the FIELD rather than the POINTING table

• refant (stringVec=’’) - use the WVR data from this antenna for calculating the dT/dL parameters (can give ranked list)

• offsetstable (string=’’) - (experimental) subtract the temperature offsets in this table from the WVR measurements before calculating the phase corrections

Description

Information about the observation and the performance of wvrgcal is written to the CASA logger and also returned in a dictionary. The dictionary element ‘success’ is True if no errors occured. Of particular note is the discrepancy statistic (Disc), where 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 $$\mu$$ m in all antennas have currently been found to indicate that wvrgcal correction should not be used.

Parameter descriptions

vis

Name of input visibility file. Default: none. Examples: vis=’ngc5921.ms’

caltable

Name of output gain calibration table. Default: none. Examples: 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: [ ]. Examples: tie=[‘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: [ ]. Examples: sourceflag=[‘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: [ ]. Examples: wvrflag=[‘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). Examples: smooth=’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). Examples: spw=[17,19,21,23]

wvrspw

List of the spectral window IDs from which the WVR data should be taken. Default: [ ] (all WVR spectral windows). Examples: wvrspw=[0]

reversespw

Reverse the sign of the correction for the listed SPWs (only neede for early ALMA data before Cycle 0). Default: ‘’ (none). Examples: 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 (0.0 to 1.0), 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: refant=’DA45’ - use DA45; refant=[‘DA45’,’DV51’] - use DA45 and if that is not good, use DV51 instead.

offsetstable

Subtract the temperature offsets in this table from the WVR measurements before using them to calculate the phase corrections (experimental). Default: ‘’ (do not apply any offsets). Examples: offsetstable=’uid___A002_Xabd867_X2277.cloud_offsets’ use the given table.

Examples

Usage

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')

Development

No additional development details

Parameter Details

Detailed descriptions of each function parameter

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