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astro-ph.EP · Earth and Planetary Astrophysicsastro-ph.IM · Instrumentation and Methods for Astrophysics

Ten TESS sectors do not give a stable detection of a change in WASP-18 b eclipse spacing

We measure the time from primary transit to secondary eclipse in ten public 120-second TESS SPOC sectors for WASP-18 b from 2018 to 2026. Symmetric templates and a separate quadratic background for each event fit 209 transits and 208 eclipses. The primary recent-minus-early spacing change is +55 seconds. A bootstrap of complete orbital cycles gives a conditional 95 percent interval of -22 to +128 seconds. Two-cycle blocks also include zero. Three-cycle blocks exclude zero when sector weights are estimated again. All three block intervals include zero when the primary sector weights are held fixed. Eight fit changes give point contrasts from +39 to +59 seconds with these fixed weights. Sector 105 has a 189 second spacing difference between PDC and SAP flux. Numerical integration and independent fits agree closely. A tested smooth phase curve gives less than 2.2 seconds of spacing bias. The data do not give a stable detection of changed orbital geometry. A comparison with a published precession rate depends on absolute timing assumptions. We give no precession limit. The new spacing table, original light curves, source hashes, event cuts, code, bootstrap draws, figures, and reproduction instructions are preserved. The intervals do not cover arbitrary errors shared by a sector or unknown planet brightness maps.

WASP-18 b · TESS · secondary eclipse · transit timing · apsidal precession · cycle bootstrap · public data

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References

7
  1. usesFour 2026 TESS sector means show WASP-18 b transits 41 seconds before the printed linear clock sci:sha256:e2feb9440fb1c6efe0d39ee0538714bab0fc56d66e7885f994f6e330411dd4ee

    We use its frozen public input records and transit clock context. We measure eclipse minus transit spacing.

  2. usesFixed-shape eclipse fits to TESS sectors 96 and 103–106 do not resolve a depth change in WASP-18 b sci:sha256:941dee6ee301412c38413dc6d0e026a8e7eb7bab5ca809c25e46e9a386411d8f

    We use its preserved ten TESS light curves and public archive provenance. This work fits event times instead of holding eclipse time fixed.

  3. usesdoi:10.17909/t9-nmc8-f686

    This collection supplies the original TESS SPOC light curves. File URLs and SHA-256 hashes identify the exact products.

  4. usesdoi:10.1051/0004-6361/202450939

    This paper supplies geometry, the coordinate ephemeris, and the light travel time. It also gives prior eclipse timing results and brightness-map limits.

  5. doi:10.3847/1538-3881/ae75e8

    We compare measured spacings with its stated eccentricity and precession rate under explicit timing assumptions. We do not reproduce its velocity posterior.

  6. doi:10.1051/0004-6361/201834376

    This paper gives prior radial velocity evidence for precession.

  7. usesdoi:10.1086/683602

    batman supplies the transit model and an independent eclipse template check.

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