Utility Functions

Utility methods.

utils.stokes_to_coherency(stokes_arr)

Convert Stokes array to coherency matrix.

Parameters

stokes_arr (Quantity) – Array of stokes parameters in order [I, Q, U, V], shape(4,) or (4, Nfreqs, Ncomponents).

Returns

coherency matrix (array of float) – Array of coherencies, shape (2, 2) or (2, 2, Nfreqs, Ncomponents)

utils.coherency_to_stokes(coherency_matrix)

Convert coherency matrix to vector of 4 Stokes parameter in order [I, Q, U, V].

Parameters

coherency matrix (Quantity) – Array of coherencies, shape (2, 2) or (2, 2, Ncomponents)

Returns

stokes_arr (array of float) – Array of stokes parameters, shape(4,) or (4, Ncomponents)

utils.jy_to_ksr(freqs)

Calculate multiplicative factors to convert [Jy] to [K sr].

Parameters

freqs (astropy.Quantity or array_like of float (Deprecated)) – Frequencies, assumed to be in Hz if not a Quantity.

Returns

Quantity – Conversion factor(s) to go from [Jy] to [K sr]. Shape equal to shape of freqs.

utils.download_gleam(path='.', filename='gleam.vot', overwrite=False, row_limit=None)

Download the GLEAM vot table from Vizier.

Parameters

• path (str) – Folder location to save catalog to.

• filename (str) – Filename to save catalog to.

• overwrite (bool) – Option to download the file even if it already exists.

• row_limit (int, optional) – Max number of rows (sources) to download, default is None meaning download all rows.