ApplyBeam

Apply the LOFAR beam model, or the inverse of it.

inputs

type

type:

string

default:

applybeam

doc:

Case-insensitive step type; must be ‘applybeam’ .

beammode

type:

enum

default:

default

doc:

Beam mode to apply, can be array_factor, element, full, or default (same as full). The mode full applies both the element beam and the array factor .

symbols:

array_factor, element, full, default

beamproximitylimit

type:

float

default:

60

doc:

Specified in arcseconds, and if non-zero, sources that are near each other are clustered and the beam is only calculated for each cluster. This trades an increase in speed for a very low level of loss in accuracy. This parameter is ignored in the ApplyBeam step itself, and should instead be used as part of predict, ddecal, gaincal, h5parmpredict, etc. This parameter has been introduced in Dec 2020 .

direction

type:

string?

doc:

A RA/Dec value specifying in what direction to correct the beam. See phaseshift.phasecenter for syntax. If empty, the beam is corrected in the direction of the current phase center.

invert

type:

boolean?

default:

True

doc:

Invert the corrections, to correct the data. Default is true. If you want to corrupt the data, set it to false .

onebeamperpatch

type:

string?

default:

False

doc:

Deprecated: use beamproximitylimit instead. When true, computes the beam only for the center of each patch (saves computation time, but you should set this to false for large patches). In the ApplyBeam step, this setting does not make sense (but it does if the applybeam is part of predict, ddecal, gaincal, h5parmpredict, etc.). Generally, false is the right setting for this option. The default has changed to false in Nov 2018 .

step_name

type:

string

default:

applybeam

doc:

unique name for the step .

updateweights

type:

boolean?

doc:

Update the weights column, in a way consistent with the weights being inverse proportional to the autocorrelations (e.g. if ‘autoweights’ was used before) .

usechannelfreq

type:

boolean?

default:

True

doc:

Compute the beam for each channel of the measurement set separately. This is useful for merged / concatenated measurement sets. For raw LOFAR data you should set it to false, so that the beam will be formed as in the station hardware. Also, setting it to false is faster .