A 100-transit timing model gives Shklovskii signal-to-noise above five for 22 catalog hosts at one-second errors over 20 years

We test a fixed timing budget for the Shklovskii transit timing term. The model assumes a constant intrinsic planet clock and rectilinear stellar motion. It fits a free epoch and period. For a quadratic endpoint delay K and independent time errors sigma_i, the conditional signal-to-noise ratio has the sharp upper bound K sqrt(sum_i 1/sigma_i^2)/8. We apply this bound to a frozen NASA Exoplanet Archive response from 24 October 2026. Of 3,338 selected hosts listed with one star, 22 have nominal ceilings above five for 100 one-second transit times in 20 years. Schedules on 100 distinct transit cycles also exceed five for all 22. These schedules remain above five over the stated catalog error boxes and a separate test with extra astrometric allowances. The boxes have no assigned probability. HD 136352 has the largest nominal schedule value, 22.252. We also use the cycle numbers, source periods, and quoted errors of 7,454 published transit times from 304 matched systems in the Ivshina and Winn 2022 catalog. Their largest conditional design value is 0.024605, at WASP-4. We do not fit their measured timing residuals. The contribution is a timing-budget bound, a frozen target table, distinct-cycle schedules, and a published-sampling sensitivity test. It is not a measured acceleration or a planet discovery. Correlated errors, sky visibility, intrinsic period change, and other dynamics can limit practical use. Code, input data, provenance, figures, selection decisions, and independent checks are included.

transit timing · Shklovskii effect · proper motion · exoplanets · observing design · NASA Exoplanet Archive · reproducible research