ULTRA l1b add backup method for getting spin information

[lacoak21]

Change Summary

I discovered that sometimes the de data may be associated with spins that are NOT in the aux dataset. I talked to Nick and Larry about this issue and getting the data from the universal spin table is the desired way to deal with this.

Updated Files

• updated file 1
  • description of change 1 in file 1
  • description of change 2 in file 2
• updated file 2
  • descipriton of change 1 in file 2

Testing

Fix test and test new backup method

[Copilot]

Pull request overview

This pull request adds a backup mechanism to retrieve spin information from the universal spin table when events fall outside the auxiliary dataset's time range. This addresses an edge case where direct event (DE) data may be associated with spins not present in the aux dataset.

Key Changes:

• Refactored get_spin_and_duration() to get_spin_info() which returns a complete xarray Dataset with spin information
• Added fallback logic to query the universal spin table for events outside aux dataset coverage
• Updated get_event_times() parameter order for consistency (de_event_met before phase_angle)

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
imap_processing/ultra/l1b/ultra_l1b_extended.py	Core implementation: refactored spin info retrieval functions, added universal spin table fallback, and updated get_event_times signature
imap_processing/ultra/l1c/ultra_l1c_pset_bins.py	Updated calls to get_spin_info and added aux_dataset parameter to functions requiring spin information
imap_processing/ultra/l1c/spacecraft_pset.py	Passed aux_dataset to get_spacecraft_exposure_times
imap_processing/ultra/l1c/helio_pset.py	Passed aux_dataset to get_spacecraft_exposure_times
imap_processing/ultra/l1b/de.py	Updated to use get_spin_info and pass spin_ds to get_event_times
imap_processing/ultra/l1b/ultra_l1b_culling.py	Updated to use get_spin_info instead of get_spin_and_duration
imap_processing/ultra/constants.py	Extracted N_RE constant for better maintainability of earth culling radius calculation
imap_processing/tests/ultra/unit/test_ultra_l1c_pset_bins.py	Updated test calls to match new function signatures with aux_dataset parameter
imap_processing/tests/ultra/unit/test_ultra_l1b_extended.py	Updated tests to use get_spin_info and verify fallback behavior with universal spin table
imap_processing/tests/ultra/unit/test_ultra_l1b_culling.py	Updated tests to use get_spin_info instead of get_spin_and_duration

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[greglucas]

It seems like we would want to use one or the other, but not switch between two as that could confuse things later on. If we don't have enough aux packet data, do we need to increase the request period on batch_starter to include some earlier packets for Ultra? In the opposite direction, if we always have spin table data, could we always reference that table instead of mixing and matching the two different sources of data?

[subagonsouth]

Looks good except for the one concern I have about the units of subseconds in the two different sources for spin info.