ngcasa.imaging.make_gridding_convolution_function

make_gridding_convolution_function(mxds, gcf_parms, grid_parms, sel_parms)[source]

Currently creates a gcf to correct for the primary beams of antennas and supports heterogenous arrays (antennas with different dish sizes). Only the airy disk and ALMA airy disk model is implemented. In the future support will be added for beam squint, pointing corrections, w projection, and including a prolate spheroidal term.

Parameters

  • vis_dataset (xarray.core.dataset.Dataset) – Input visibility dataset.

  • gcf_parms (dictionary) –

  • gcf_parms['function'] ({'casa_airy'/'airy'}, default = 'casa_airy') – The primary beam model used (a function of the dish diameter and blockage diameter).

  • gcf_parms['list_dish_diameters'] (list of number, units = meter) – A list of unique antenna dish diameters.

  • gcf_parms['list_blockage_diameters'] (list of number, units = meter) – A list of unique feed blockage diameters (must be the same length as gcf_parms[‘list_dish_diameters’]).

  • gcf_parms['unique_ant_indx'] (list of int) – A list that has indeces for the gcf_parms[‘list_dish_diameters’] and gcf_parms[‘list_blockage_diameters’] lists, for each antenna.

  • gcf_parms['image_phase_center'] (list of number, length = 2, units = radians) – The mosaic image phase center.

  • gcf_parms['a_chan_num_chunk'] (int, default = 3) – The number of chunks in the channel dimension of the gridding convolution function data variable.

  • gcf_parms['oversampling'] (list of int, length = 2, default = [10,10]) – The oversampling of the gridding convolution function.

  • gcf_parms['max_support'] (list of int, length = 2, default = [15,15]) – The maximum allowable support of the gridding convolution function.

  • gcf_parms['support_cut_level'] (number, default = 0.025) – The antennuation at which to truncate the gridding convolution function.

  • gcf_parms['chan_tolerance_factor'] (number, default = 0.005) – It is the fractional bandwidth at which the frequency dependence of the primary beam can be ignored and determines the number of frequencies for which to calculate a gridding convolution function. Number of channels equals the fractional bandwidth devided by gcf_parms[‘chan_tolerance_factor’].

  • grid_parms (dictionary) –

  • grid_parms['image_size'] (list of int, length = 2) – The image size (no padding).

  • grid_parms['cell_size'] (list of number, length = 2, units = arcseconds) – The image cell size.

Returns

gcf_dataset

Return type

xarray.core.dataset.Dataset