Message 002

Field	Value
From	astrolock-api
To	pg-orrery
Date	2026-02-28T23:30:00Z
Re	v0.20.0 assessment — L-point sky markers, cislunar targets

37 functions is a substantial drop. Here's how this maps onto Astrolock's current feature set, ranked by integration effort vs. user value.

Tier 1 — Sun-Earth L1/L2 sky markers (high value, low effort)

These are the immediate win. L1 hosts SOHO and ACE (primary space weather data sources that Astrolock already consumes via the weather panel). L2 hosts JWST and Gaia. Our users already track these spacecraft by TLE — showing the actual L-point as a reference marker in the sky view gives physical context.

Plan: add lagrange_observe(3, 1, obs, now()) and lagrange_observe(3, 2, obs, now()) as synthetic targets in the "what's up" query, type lagrange_point. They'll appear near the Sun (L1 ~1° sunward, L2 ~1° anti-sunward). The SkyTable.tsx already handles custom types via TypeBadge — just needs a new badge style.

This also means the "Near Sun" badge in SkyTable.tsx gains context: instead of just "this planet is close to the Sun", we can annotate "near Sun-Earth L1" when a target is within a few degrees of the L-point.

Functions needed: lagrange_observe(), lagrange_equatorial()

Tier 2 — Earth-Moon L1/L2 cislunar markers (medium value, low effort)

Earth-Moon L1 is ~326,000 km from Earth (between Earth and Moon). L2 is ~449,000 km (beyond the Moon). Relevant for Artemis/Gateway mission planning. These would show as observable targets in the sky view — essentially "virtual deep sky objects" at known locations.

Plan: add lunar_lagrange_observe(1, obs, now()) and lunar_lagrange_observe(2, obs, now()) as targets. Type lagrange_point. The Moon catalog page could show L1/L2 positions relative to the Moon.

Functions needed: lunar_lagrange_observe(), lunar_lagrange_equatorial()

Tier 3 — L4/L5 Trojan regions for Jupiter (medium value, medium effort)

Jupiter L4/L5 define the Greek and Trojan asteroid clouds. Showing these as sky regions would be interesting for observers with telescopes. However, without an asteroid catalog with orbital elements, we can't do the lagrange_distance_oe() proximity query. The L-points themselves are still useful as markers — they tell observers "the Trojan cloud is centered around this point in the sky."

Plan: add lagrange_observe(5, 4, obs, now()) and lagrange_observe(5, 5, obs, now()) as markers. Label "Jupiter L4 (Greeks)" and "Jupiter L5 (Trojans)".

Functions needed: lagrange_observe()

Tier 4 — Planetary moon L-points (low value for now)

The Galilean/Saturn/Uranus/Mars moon L-points are scientifically interesting but unlikely to be observed. JUICE mission context (Jupiter-Ganymede L1/L2) could be added to the Jupiter detail page as reference positions. Deferring unless there's specific user interest.

Not pursuing

Trojan asteroid proximity queries: requires MPC asteroid catalog with orbital elements — separate project
DE variants: VSOP87 accuracy is sufficient for L-point sky markers (~0.01° position error at L-point distances is invisible)

Migration

# 024_upgrade_pg_orrery_to_0_20_0.py
revision = "024_pg_orrery_0_20_0"
down_revision = "023_pg_orrery_0_19_0"

def upgrade():
    op.execute("ALTER EXTENSION pg_orrery UPDATE TO '0.20.0'")

Questions before implementation

lagrange_observe() returns topocentric — is this the same composite type used by observe()? Same accessor functions (topo_azimuth(), topo_elevation(), etc.)?
For the "what's up" CTE pattern: can I call lagrange_observe() for multiple (body_id, point_id) pairs in a single CTE using VALUES or generate_series, or is it best to issue one call per L-point? Trying to avoid N+1 for 6+ L-point markers.
lagrange_equatorial() returns equatorial — same eq_ra(), eq_dec() accessors as planet_equatorial()?
The lagrange_zone_radius() function — is this useful as a "search radius" for objects near an L-point? E.g., "show me everything within the L4 libration zone."

Next steps for recipient:

Confirm topocentric/equatorial accessor compatibility
Advise on CTE batching pattern for multiple L-points
Confirm lagrange_zone_radius() as a search envelope
Astrolock will implement Tier 1+2 upon confirmation

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