Visibility

class Visibility(frequency=None, channel_bandwidth=None, phasecentre=None, configuration=None, uvw=None, time=None, vis=None, weight=None, integration_time=None, flags=None, baselines=None, polarisation_frame=<rascil.data_models.polarisation.PolarisationFrame object>, imaging_weight=None, source='anonymous', meta=None, low_precision='float64')

Bases: Dataset

Visibility xarray Dataset class

Visibility is defined to hold an observation with one direction.

The phasecentre is the direct of delay tracking i.e. n=0. If uvw are rotated then this should be updated with the new delay tracking centre.

Polarisation frame is the same for the entire data set and can be stokesI, circular, circularnp, linear, linearnp

The configuration is stored as an attribute.

Here is an example:

<xarray.Visibility>
Dimensions:            (baselines: 6670, frequency: 3, polarisation: 4, time: 3, uvw_index: 3)
Coordinates:
  * time               (time) float64 5.085e+09 5.085e+09 5.085e+09
  * baselines          (baselines) MultiIndex
  - antenna1           (baselines) int64 0 0 0 0 0 0 ... 112 112 112 113 113 114
  - antenna2           (baselines) int64 0 1 2 3 4 5 ... 112 113 114 113 114 114
  * frequency          (frequency) float64 1e+08 1.05e+08 1.1e+08
  * polarisation       (polarisation) <U2 'XX' 'XY' 'YX' 'YY'
  * uvw_index          (uvw_index) <U1 'u' 'v' 'w'
Data variables:
    integration_time   (time) float32 99.72697 99.72697 99.72697
    datetime           (time) datetime64[ns] 2000-01-01T03:54:07.843184299 .....
    vis                (time, baselines, frequency, polarisation) complex128 ...
    weight             (time, baselines, frequency, polarisation) float32 0.0...
    imaging_weight     (time, baselines, frequency, polarisation) float32 0.0...
    flags              (time, baselines, frequency, polarisation) int32 0.0...
    uvw                (time, baselines, uvw_index) float64 0.0 0.0 ... 0.0 0.0
    uvw_lambda         (time, baselines, frequency, uvw_index) float64 0.0 .....
    uvdist_lambda      (time, baselines, frequency) float64 0.0 0.0 ... 0.0 0.0
    channel_bandwidth  (frequency) float64 1e+07 1e+07 1e+07
Attributes:
    phasecentre:         <SkyCoord (ICRS): (ra, dec) in deg    (180., -35.)>
    configuration:       <xarray.Configuration>Dimensions:   (id: 115, spat...
    polarisation_frame:  linear
    source:              unknown
    meta:                None

Methods Summary

to_native_dataset()

Convert to plain Dataset.

Methods Documentation

to_native_dataset()

Convert to plain Dataset. Needed, e.g., for xarray.concat. This makes sure that the child class is represented as its parent class.