matvis.coordinates.calc_coherency_rotation

matvis.coordinates.calc_coherency_rotation(ra, dec, alt, az, time, location)[source]

Compute the rotation matrix needed for time-dependent coherency calculation.

This function computes the rotation matrix needed to rotate a source’s coherency from equatorial (RA/Dec) frame into the local alt/az frame. Adopted from the pyradiosky coherency calculation, but modified for better vectorization. Coordinate rotations should be performed before running this function.

Parameters:

  • alt (array_like) – Altitude angle(s) of source(s), in radians.

  • az (array_like) – Azimuth angle(s) of source(s), in radians. Same shape as alt.

  • time (astropy.time.Time) – Observation time, used to compute the ICRS→altaz rotation.

Returns:

coherency_rot_matrix – 2x2 rotation matrix that carries the coherency from the equatorial frame to the alt/az frame. Shape=(2, 2, N), where N is the number of sources.

Return type:

array_like