[leowerneck]

Change Summary

Related to #21.

Overview

This PR is a simplified version of #165 intended to add the transformation to GSE coordinates in the Earth frame. It does not introduce GSM or HAE-J2000, which will be left for a future PR (if still desired).

Testing

All newly added tests pass locally.

Note

The vast majority of the diff in this commit is due to reformatting with ruff format, which mostly affect the test files.

[leowerneck]

@hafarooki Your review would also be appreciated.

[jtniehof]

My big question before looking at details: have we confirmed exactly what WIND is reporting as GSE? Is it GSE relative to Sun, GSE less a fixed 30km/s in Y, or a "proper" aGSE rotated into SW (nominal or actual)? Since matching WIND (and other L1) is a key driver, we should be as precise as we can. Has someone looped in with Savvas?

(Slow on the uptake here because I've been focusing on the release 2 issues).

[leowerneck]

After discussions with @mmshaw and @mecuesta, combined with the result of the long email thread, my understanding is that IMAP will report GSE in the Earth's frame, and that it should be called "_gse" (not "_gse_earth"). We won't try to match other missions if they use something else.

My goal for this PR was to introduce GSE (not aGSE) coordinates in the Earth's frame. The steps I took were:

• Rotate the Sun-frame RTN velocity into ECLIPJ2000.
• Use SPICE to subtract Earth's velocity.
• Use SPICE to apply a full 6x6 state transform from ECLIPJ2000 to GSE.

Hameed can correct me if I'm wrong, but I believe he found that WIND/OMNI use GSE coordinates in the Sun's frame. I haven't looped in with Savvas.

[leowerneck]

Pinging @mmshaw and @mecuesta for comments.

[jtniehof]

Couple of small metadata change requests and a query on the approach...I don't think anything major needs to be changed.

[leowerneck]

@jtniehof Should be ready for your review. Opened companion PR IMAP-Science-Operations-Center/sds-data-manager#1747.

[jtniehof]

One further little nitpick on the transform...

[jtniehof]

I do think this should still be the six-component state transform for velocity from RTN to GSE

[leowerneck]

Doesn't:

    imap_state_gse = imap_state(et, SpiceFrame.IMAP_GSE, observer=SpiceBody.EARTH)
    imap_velocity_gse = imap_state_gse[3:]

already include the dR/dt term? I thought the point was to let SPICE handle the sxform calls under the hood instead of calling them explicitly in the code.

The test test_convert_sun_velocity_rtn_to_gse_matches_full_state_transform was intended to ensure that the current RTN -> GSE approach matches the previous RTN -> J2000 -> GSE, so I thought I was doing the right thing.

[jtniehof]

Oh! Right! The dR/dt term is going to be lumped in with the spacecraft velocity transform. I was thinking in terms of doing it with the plasma velocity transform. Nice catch.

[jtniehof]

all good!

[jtniehof]

I'm marking as Validating status until we deploy and reprocess and check.

EDIT: As Leo noted, after release 2 is done.