dft_skycomponent

ska_sdp_func_python.imaging.dft.dft_skycomponent(uvw: ndarray, skycomponent: SkyComponent, phase_centre: SkyCoord) → ndarray

Calculate the Direct Fourier Transform (DFT) for a single sky component.

This function computes the visibility contribution of a sky component by calculating the phase delay associated with its position relative to the phase centre. It accounts for wide-field effects (w-term) and applies Gaussian tapering if the component shape is defined as such.

Parameters

uvwnumpy.ndarray

The UVW coordinates of the baselines in metres. Expected shape: (n_times, n_baselines, 3).

skycomponentSkyComponent

The sky component object to transform. It must contain the following attributes:

• frequency: Array of shape (n_freqs,).

• flux: Array of shape (n_freqs, n_pols).

• direction: SkyCoord object representing the source position.

• shape: String indicating shape (e.g., “GAUSSIAN”, “POINT”).

• params: Dictionary of shape parameters (if Gaussian).

phase_centreSkyCoord

The phase centre of the observation, used as the reference point for calculating direction cosines ($l, m, n$).

Returns

numpy.ndarray

The calculated visibilities for the component. Shape: (n_times, n_baselines, n_freqs, n_pols).