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Fix GCRS to J2000 frame bias in tleHandling - #1622
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Description
tleHandling.frame_bias()returnedR3(dalpha0) R2(-xi0) R1(-eta0). The IERS frame bias from the GCRS to the mean equator and equinox of J2000 isR1(-eta0) R2(xi0) R3(dalpha0), so the rotations were applied in reverse order andxi0had the wrong sign._teme2j2000()applies the transpose of this matrix to go from mean J2000 to the Basilisk inertial frame (J2000/ICRF), andommHandlingreuses_teme2j2000().Changes:
src/utilities/tleHandling.py:frame_bias()now returnsrot(1, -eta) @ rot(2, xi) @ rot(3, d_alpha). The bias constants are unchanged. The function now has a docstring, and the constants have unit comments._teme2j2000()andommHandlingneed no changes.Verification
Reference values were computed with Orekit 13.1 (
orekit_jpype13.1.8.0):frame_bias()vs. Orekit GCRF → EME2000 at J2000 (max element difference)_teme2j2000()vs. Orekit TEME → GCRF, position error_teme2j2000()vs. Orekit TEME → GCRF, velocity errorTwo regression tests were added to the existing
src/tests/test_readTLE.py:test_frame_bias_matches_orekit: comparesframe_bias()with Orekit's GCRF → EME2000 rotation.test_teme2j2000_matches_orekit: converts a LEO TEME state at 2004-04-06 07:51:28.386009 UTC and compares it with Orekit's TEME → GCRF result.Both tests fail with the previous formula and pass with the fix.
test_readTLE.py,test_readOMM.py, andtest_scenarioConstellationFromTle.pyall pass.Documentation
docs/source/Support/bskKnownIssues.rst.Future work
None.