fetchExoplanets placed each star it adds from the Exoplanet Archive by carrying the archive's
position back sixteen years, and 4c8e4a0 said the archive publishes at Gaia's J2016. It does not:
its positions are Gaia DR2's at J2015.5 although it names the DR3 source. Barnard's star in the
archive, 269.4486144, 4.7379808, equals DR2 4472832130942575872 at J2015.5 to 1e-7°, and sits 5.2″
from DR3's J2016 place; the review found 66 of the 67 archive-placed stars moving over 100 mas a
year within 0.21 mas of their DR2 position and none within 1 mas of DR3's. The matcher's comment
made the same claim of HD 133131 and TOI-2459, whose positions are DR2's too.
host-star-matching.ts now exports CATALOGUE_EPOCH and ARCHIVE_EPOCH = 2015.5, the matcher carries a
query back by their difference, and fetchExoplanets uses the same two, so the epoch is written
once. From cache: only the 3 277 archive-placed stars move, 2 287 of them by more than a
milliarcsecond, 74 by more than 50 and TOI-2406 most, by 203 mas, half a year of its 405 mas/yr;
no planet changes host. Invisible at map scale; the point is that the constant and its comments
now say what the archive does.
Control: ARCHIVE_EPOCH back to 2016.0 fails "carries Barnard's star from the archive's position to
where Gaia DR3's goes, to a few milliarcseconds" (1 of 802), which puts the two 5.2″ apart. The
GJ 15 A matching fixture is now built at J2015.5 too. fetchExoplanets' use of the constant has no
test of its own; the ETL has no test harness.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
SenrokaiandClaude Opus 5.5
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