ConvolutionFunction
- class ska_sdp_datamodels.gridded_visibility.ConvolutionFunction(data_vars=None, coords=None, attrs=None)[source]
Bases:
DatasetClass to hold Convolution function for Fourier processing - Has four or more coordinates: [chan, pol, z, y, x] where x can be u, l; y can be v, m; z can be w, n.
The cf has axes [chan, pol, dy, dx, y, x] where z, y, x are spatial axes in either sky or Fourier plane. The order in the WCS is reversed so the grid_WCS describes UU, VV, WW, STOKES, FREQ axes.
The axes UU,VV have the same physical stride as the Image. The axes DUU, DVV are sub-sampled.
Convolution function holds the original sky plane projection in the projection_wcs.
Here is an example:
<xarray.ConvolutionFunction> Dimensions: (du: 8, dv: 8, frequency: 1, polarisation: 1, u: 16, v: 16, w: 1) Coordinates: * frequency (frequency) float64 1e+08 * polarisation (polarisation) <U1 'I' * w (w) float64 0.0 * dv (dv) float64 -1.031e+05 -7.735e+04 ... 7.735e+04 * du (du) float64 -1.031e+05 -7.735e+04 ... 7.735e+04 * v (v) float64 -1.65e+06 -1.444e+06 ... 1.444e+06 * u (u) float64 -1.65e+06 -1.444e+06 ... 1.444e+06 Data variables: pixels (frequency, polarisation, w, dv, du, v, u) complex128 0j ...... Attributes: data_model: ConvolutionFunction grid_wcs: WCS Keywords Number of WCS axes: 7 CTYPE : 'UU' ... projection_wcs: WCS Keywords Number of WCS axes: 4 CTYPE : 'RA--... polarisation_frame: stokesI
Methods Summary
constructor(data[, cf_wcs, polarisation_frame])Create ConvolutionFunction
Methods Documentation