feat: add non-sidereal tracking for solar system objects

[dgegen]

Pull Request

Description
Adds non-sidereal (differential) tracking support for solar system objects. A NonSiderealManager pre-computes a cubic-interpolated ephemeris at sequence start so that ASCOM RightAscensionRate/DeclinationRate can be refreshed each exposure without repeated get_body() calls. Periodic re-centering slews correct long-term drift.

I have locally tested integration with JPL Horizons via astroquery to allow the tracking of comets and asteroids. However, to maintain Astra’s "Offline-First" philosophy and avoid mandatory network dependencies, I have not yet included this in the current PR. That said, I am happy to do so following a discussion on Astra’s connectivity requirements and how to handle offline 'field mode' scenarios for minor body lookups gracefully.

Let me know what you think!

Related Issue
Closes #91

Changes Made

• nonsidereal.py: New NonSiderealManager class encapsulating setup, rate application, re-centering, and cleanup
• utils.py: Add is_solar_system_body, precompute_ephemeris, compute_nonsidereal_rates_from_interp; cache _SOLAR_SYSTEM_BODIES and _SOLAR_TO_SIDEREAL at module level
• observatory.py: Integrate NonSiderealManager into the imaging sequence loop with guiding-incompatibility warning and guaranteed rate reset in a finally block
• action_configs.py: Add nonsidereal_recenter_interval field; update guiding field description; add usage documentation with a Saturn scheduling example
• tests/test_utils.py: Fix monkeypatch targets for get_body; add full test suite for the three new utility functions

How to Test

1. Schedule an object action with a solar system body (e.g. "lookup_name": "saturn") and "nonsidereal_recenter_interval": 300
2. Verify tracking rates are applied at the start of each exposure
3. Verify the telescope re-slews to the updated ephemeris position every 300 s
4. Verify that enabling guiding: true alongside non-sidereal tracking logs a warning and disables guiding
5. Run pytest tests/test_utils.py — all non-sidereal utility tests should pass

Checklist

• Code follows project style guidelines
• Tests added/updated
• Documentation updated (if needed)
• All checks pass

[Copilot]

Pull request overview

Adds non-sidereal (differential) tracking support aimed at enabling solar system object imaging by precomputing ephemerides and applying ASCOM RA/Dec tracking rates during sequences, with optional periodic re-centering slews.

Changes:

• Introduces NonSiderealManager to encapsulate ephemeris setup, rate application, periodic re-centering, and cleanup/reset.
• Extends astra.utils with solar-system body detection, ephemeris precomputation, and nonsidereal rate computation from interpolators.
• Integrates non-sidereal tracking into the main imaging sequence loop, including guiding incompatibility handling and cleanup in finally.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/astra/nonsidereal.py	New manager implementing nonsidereal tracking workflow for a sequence.
src/astra/utils.py	Adds helpers for solar-system body lookup, ephemeris interpolation, and rate computation.
src/astra/observatory.py	Wires the manager into image_sequence (initial rates, re-centering, cleanup/reset).
src/astra/action_configs.py	Adds nonsidereal_recenter_interval config field and documents usage.
tests/test_utils.py	Updates get_body monkeypatch target and adds tests for new utils helpers.
uv.lock	Lockfile change (greenlet wheel entry adjustment).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[dgegen]

Following a discussion with @ppp-one, I've now included the JPL Horizons integration via astroquery that I previously held back.

The implementation raises NotMovingBodyError when a lookup_name can't be resolved as a known solar system body, which triggers a fallback to Horizons for comets and asteroids. This does introduce a network dependency at schedule load time for minor bodies.

For field mode / offline scenarios, the current behaviour is: if the Horizons query fails with anything other than a ConnectionError, it raises NotMovingBodyError and the object is treated as a fixed target (sidereal tracking and lookup). A bare ConnectionError propagates so the operator knows the schedule couldn't be validated. It might be worth to consider a softer fallback (e.g. warn and skip the action rather than abort).