Find the hosts the catalogue already holds, and name them after their planets' star

The archive's default-parameter rows leave sy_dist blank for 100 planets, TRAPPIST-1's seven
among them, so the matcher could not place a host the catalogue had drawn since the Gaia
nearby query (Gaia DR3 2635476908753563008, 12.47 pc). fetchExoplanets now also reads the
Planetary Systems Composite table (pscomppars) and fills a default row's blank host cells from
it. Only host columns: a composite row takes each column from its own reference, so orbits
still come from the default row alone, one fit per planet. Where both tables give a distance or
a position they agree on all 6 225 and 6 352 rows.

Three hosts the catalogue holds by name failed the distance ratio test because the archive's
sy_dist, from TICv8, contradicts its own parallax: Lalande 21185 (GJ 411) 5.68 pc against
392 mas, Luyten's Star (GJ 273) 5.92 against 263 mas, Struve 2398 B (Gl 725 B) 6.84 against
285 mas. resolveHostStarId now takes the archive's parallax (sy_plx) as a second distance the
ratio test accepts. It is a second chance, not a replacement: 47 of 5 959 systems disagree past
the tolerance, and for faint far hosts the inverse parallax is the worse figure (K2-238: 538 pc
by sy_dist, 6 779 by parallax).

Planets on a catalogue star: 2 071 -> 2 090 of 6 354. The 19 gained are TRAPPIST-1 (7),
GJ 273 (2), GJ 411 (2), Gl 725 B, HD 62509 (Pollux), K2-65, TOI-2267 A and B, and two
brown-dwarf hosts, 2MASS J02192210-3925225 and DENIS-P J082303.1-491201. No planet lost or
changed its host.

A matched host whose catalogue name is a bare Gaia designation now takes the archive's host
name, so search finds TRAPPIST-1, Teegarden's Star, TOI-700, LP 791-18 and K2-18: 575 stars
renamed. validateExoplanets refuses a host that is still only a designation, and the star
assets are rewritten after the exoplanets for that reason; stars.bin and stars-meta.bin are
unchanged. TOI-2267 A and B both land on one Gaia entry, which takes the name TOI-2267 A.

Each planet also carries its host's radius, effective temperature and luminosity (10^st_lum),
and a mass for 6 344 planets instead of 5 474, from the default row where it gives one and the
composite table otherwise, for the star-physics step.

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

src/app/shared/astro/host-star-matching.spec.ts

@@ -109,6 +109,17 @@ describe('resolveHostStarId', () => {
       expect(id).toBeNull();
     });
 
+    // The archive's 5.92 pc is TICv8's; its own parallax, 263.26 mas, says 3.80 pc, which is the
+    // star's. With the parallax given, the same query is Luyten's Star — and a parallax that
+    // contradicts the star as well rescues nothing.
+    it("accepts the archive's parallax where its sy_dist contradicts the star", () => {
+      const luytens = star(100, "Luyten's Star", 111.8496, 5.2258, 3.79);
+      const query = { hostname: 'GJ 273', raDeg: 111.8496, decDeg: 5.2258, distancePc: 5.921535 };
+
+      expect(resolveHostStarId({ ...query, parallaxMas: 263.26 }, [luytens])).toBe(100);
+      expect(resolveHostStarId({ ...query, parallaxMas: 168.9 }, [luytens])).toBeNull();
+    });
+
     // The tolerance is transverse — parsecs on the sky, not an angle — so the same 15″ offset
     // is a match at 50 pc and a stranger at 200 pc.
     it('scales the angular tolerance with the host distance', () => {

src/app/shared/astro/host-star-matching.ts

@@ -15,6 +15,21 @@ export interface HostStarQuery {
   /** μα·cos δ in mas/yr, as the archive publishes it (`sy_pmra`); missing means unknown. */
   pmRaMasPerYear?: number;
   pmDecMasPerYear?: number;
+  /**
+   * The archive's parallax in mas (`sy_plx`), a second distance the ratio test accepts. Its
+   * `sy_dist` comes from TICv8 and contradicts its own parallax past the tolerance for 47 of the
+   * 5 959 systems that publish both — Lalande 21185 at 5.68 pc for 392 mas (2.55 pc), Luyten's
+   * Star at 5.92 for 263 mas, Struve 2398 B at 6.84 for 285 — and those three are in the
+   * catalogue, 0.1″ to 9″ from the archive's direction. A second chance rather than a
+   * replacement: past a few hundred parsecs the inverse of a low-S/N parallax is the worse
+   * estimate (K2-238, 538 pc by `sy_dist`, would be 6 779).
+   */
+  parallaxMas?: number;
+}
+
+function distancesAgree(a: number, b: number): boolean {
+  const [near, far] = a < b ? [a, b] : [b, a];
+  return (far - near) / near <= MERGE_DISTANCE_RATIO_TOLERANCE;
 }
 
 /**
@@ -129,6 +144,7 @@ export function resolveHostStarId(
   );
   const carried = raDegDecDistanceToXyz(carriedBack.raDeg, carriedBack.decDeg, 1);
 
+  const parallaxPc = query.parallaxMas !== undefined && query.parallaxMas > 0 ? 1000 / query.parallaxMas : Number.NaN;
   const minCosine = Math.cos(Math.min(Math.PI, HOST_TRANSVERSE_TOLERANCE_PC / query.distancePc));
   let best: StarRecord | null = null;
   let bestCosine = -2;
@@ -146,8 +162,7 @@ export function resolveHostStarId(
     if (cosine < minCosine || cosine <= bestCosine) {
       continue;
     }
-    const [near, far] = query.distancePc < starDistance ? [query.distancePc, starDistance] : [starDistance, query.distancePc];
-    if ((far - near) / near > MERGE_DISTANCE_RATIO_TOLERANCE) {
+    if (!distancesAgree(query.distancePc, starDistance) && !(parallaxPc > 0 && distancesAgree(parallaxPc, starDistance))) {
       continue;
     }
     best = star;