array_layout

Tests for the functions in wodenpy.array_layout. These functions handle reading in array coords of e,n,h and converting them into X,Y,Z, used later to calculate u,v,w. Also handles precession of the array layout and LST from the simulation date back to J2000, so the array is in the same coord frame as the sky model. Should be the equivalent to rotating the sky model forward to current day and ensures the output visibilities are in the J2000 frame.

test_enh2xyz.py

array_layout.create_array_layout.enh2xyz transforms a local east, north, height coord into X,Y,Z coords, which can be used to calculate u,v,w. Tests here generate some test e,n,h coords, and then tests for two latitude test cases:

  • latitude = \(0^\circ\), should result in:

    • \(X = h\)

    • \(Y = e\)

    • \(Z = n\)

  • latitude = \(-30^\circ\), should result in:

    • \(X = \frac{n}{2} + \frac{\sqrt(3)}{2}h\)

    • \(Y = e\)

    • \(Z = \frac{\sqrt(3)}{2}n - \frac{h}{2}\)

Tested to an absolute tolerance of 1e-15.

test_RTS_PrecessXYZtoJ2000.py

array_layout.create_layout.RTS_PrecessXYZtoJ2000 takes observation date X,Y,Z coords (via a woden_settings and args object) and precesses them back to J2000 for all time steps in woden_settings.lsts. Test by giving a known set of X,Y,Z coordinates lsts and mjds, checks output precessed X,Y,Z s match the expected values stored in test_RTS_PrecessXYZtoJ2000.py. Test covers two time steps.

test_calc_XYZ_diffs.py

Tests the function array_layout.create_array_layout.calc_XYX_diffs, which takes in e,n,h coords from woden_settings and args objects, and transforms to X,Y,Z, precesses the locations back to J2000 if requested, and then calculates the baseline length in X,Y,Z.

These tests simply provide a set of known input coords for both the precession and no precession cases, and check the output values match the expected values stored in test_calc_XYZ_diffs.py.

test_RTS_precess.py

Tests the function array_layout.precession.RTS_Precess_LST_Lat_to_J2000, which takes in a current LST, latitude, and modified julian date, and precesses the LST and latitude back to J2000. Test by inputting known LSTs, latitudes, and mjds, and checking outputs match.