Io's and Europa's periapses turn backwards, held by the Laplace resonance (apsidesRegress), which
brings them to 0.07 and 0.23 degrees of Horizons from 1950 to 2100. Nothing guarded the flag: with it
dropped the ETL still passed, Io at 0.96 and Europa at 2.24 under the general 3-degree track
ceiling, their cards quietly rewriting themselves to "within 1.0" and "within 2.3". They now have
ceilings of 0.2 and 0.5, as Tethys has for the term it takes from its W. The comment on the
one-date check, which said it catches the periapsis run the wrong way, now says it does not
(0.904 against 2.5) and which check does.
Hyperion's one-date ceiling was 21 degrees, described as just above its offset on that date, where
it is 9.413: the 21 was its worst over twelve dates in an earlier check. It is now 10.
Measured on the real catalogue with the solar ETL: Io 0.07, Europa 0.23 at worst, Hyperion 9.413,
all passing. Guarded mutants, run through the solar ETL: apsidesRegress removed from both specs
fails with "Io's mean elements put it up to 0.96 degrees ... (at most 0.2 expected)"; Hyperion's row
misread by 6 degrees of node fails the one-date check at 15.41, which 21 let through.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
SenrokaiandClaude Opus 5.5
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