get_geocenter

gdt.missions.fermi.gbm.localization.dol.legacy_functions.get_geocenter(sc_quat, sc_pos, verbose=False)[source]

Get Earth center and spacecraft direction cosine matrix.

Transform from “Compendium of Co-ordinate Transformations” B Shivakumar et al. National Aerospace Laboratories. Rewritten 05/23 using MSB’s matrix (seems different)

Tested sc cosines using quaternion & x,z cosines provided by T. Burnett (toby_quat.png) 05/07. Input Toby’s quaternion to fakerates_q.txt, return correct scx, scz (scy untested).

Parameters:

  • sc_quat (np.ndarray(4, float64)) – Quaternion of the space craft. Last element is the scalar field.

  • sc_pos (np.ndarray(3, float64)) – Space craft position

  • verbose (bool) – Print info to screen when True

Returns:

  • geodir (np.ndarray(3, np.float64)) – Vector pointing from spacecraft to center of the Earth

  • geo_az (float32) – Azimuth of geodir relative to spacecraft

  • geo_zen (float32) – Zenith of geodir relative to spacecraft

  • scx (np.ndarray(3, np.float64)) – Vector along +x axis of spacecraft

  • scy (np.ndarray(3, np.float64)) – Vector along +y axis of spacecraft

  • scz (np.ndarray(3, np.float64)) – Vector along +z axis of spacecraft