Measure every moon and dwarf planet against Horizons from 1950 to 2100, and say on its card how far it strays

The clock reaches AD 1 to AD 3000, but only the planets' cards named a span their elements hold
over; the 25 moons and the four SBDB dwarf planets gave a source and an epoch, though
BodyRecord.orbitSource is documented as "the span they hold over". And the worst offsets the ETL
stated came from twelve New Year's Days: Nereid's year is 360 days, so all twelve fell far from
its periapsis, where a mean ellipse is furthest out. The one date the ETL checked, 2025-01-01, saw
Nereid at 2.6 degrees; it reaches 11.19.

For each moon and each SBDB dwarf planet the ETL now fetches Horizons' ICRF vectors from 1950 to
2100, every other day (daily for Nereid, at an eccentricity of 0.75, and Hyperion, whose row's
eccentricity is a quarter of its real one: every other day gave it 22.14, daily 22.23), and
measures how far the mean elements stray, at the same TDB dates. The card appends it: "JPL SBDB
osculating elements, epoch 2026 Jun 9, within 7.2 degrees of Horizons from 1950 to 2100". Worst
offsets on the real catalogue: the Moon 2.62 (2010 March 27), Phoebe 2.58 (1969, where a comment
claimed "within 2.0"), Phobos 1.26, Mimas 7.43, Iapetus 10.34, Nereid 11.19 (2039 Nov 1),
Hyperion 22.23 (2055 Feb 26), Ceres 7.12 (1953); Io 0.07, Titan 0.06, Eris 0.06.

build.ts recomputes each from the same Horizons positions and fails if an orbit other than
Standish's names no span, if a card states less than it strays, or if a body passes its ceiling:
3 degrees, and Hyperion 23, Nereid 12, Iapetus 11, Mimas 8 and Ceres 8, each explained. The
2025-01-01 check stays for reading errors, its comment no longer passing one date's offsets off as
worst ones. The Sun's note says the moons' and those four's elements were checked from 1950 to
2100, and the date field's description that each card says how far its orbit strays over that span.
In the running app Ceres's, Phobos's and Nereid's cards end "within 7.2", "1.3" and "11.2 degrees
of Horizons from 1950 to 2100".

The CLOCK_WINDOW comment also had the calendars the wrong way at AD 1: proleptic Gregorian dates
are two days behind the Julian calendar there, level from AD 200 to 300, and ten days ahead by
1582. It now says so, and names Ceres's drift where it named Phobos's, which its orbit now carries.

Controls: the ETL measuring nothing fails ("Ceres's orbit ... names no span it holds over"),
rounding the stated figure down fails on Ceres (7.1 against 7.12), and Nereid held to the general
ceiling fails at 11.19; the note and the date field without the span fail their named tests.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/app/features/galaxy-system/galaxy-system-scene.component.ts

@@ -1768,8 +1768,9 @@ export class GalaxySystemSceneComponent implements AfterViewInit, OnDestroy {
           : []),
       ]);
       // Where the orbits come from, and for the Sun how far from the present they hold: each
-      // body's card names its own source and epoch.
-      const source = this.bodies.some((body) => body.systemStarId === star.id) ? 'JPL mean elements, the planets’ fit for 3000 BC to AD 3000, and the SBDB’s osculating ones for Ceres, Eris, Haumea and Makemake,' : 'published elements';
+      // body's card names its own source, and for a moon or dwarf planet how far it strays from
+      // Horizons over the span it was checked.
+      const source = this.bodies.some((body) => body.systemStarId === star.id) ? 'JPL mean elements, the planets’ fit for 3000 BC to AD 3000 and the moons’ checked from 1950 to 2100, and the SBDB’s osculating ones for Ceres, Eris, Haumea and Makemake, checked over the same span,' : 'published elements';
       // Named to the minute, in UTC like the date field: a jump to 18:00 on a given day is a
       // question about that hour, and the note is where the answer says which sky it is.
       const drawnFor = `${this.time.date().toISOString().slice(0, 16).replace('T', ' ')} UTC`;