We perform a controlled search for sidereal-phase-locked transientcoincidences in superconducting gravimeter records from theInternational Geodynamics and Earth Tide Service (IGETS). We analyse two high-quality stations (, Rustrel/LSBB iGrav;, Strasbourg iOSG) using (i) a window-based pipeline onLevel-1 minute data (2020--2024) and (ii) an independentband-limited variability proxy on Level-1 second data (January 2024), derived from robust z-scored rolling RMS ofbandpass-filtered gravity in two bands (1--6\, h and 10--60\, min). Sidereal-selected windows exhibit strong cross-station structure (e. g. \ Spearman 0. 712 for 2020--2024, n=5431 pairs) and elevated joint tail activity relative torandom windows, consistent with selection of globally active epochs. However, timing specificity is not supported: the decisivesolar-time control (Gate-S), constructed by a +182-day circularshift of the sidereal driver-window schedule within 2024, yields acorrelation statistically indistinguishable from the siderealschedule (0. 927 vs. \ 0. 917;=0. 010, empirical two-sided 0. 42). A full re-evaluation shift null also does not reject the null (0. 10 in 2024). The second-resolution proxy analysis likewise shows no significantSID--RAND advantage for correlation or tail-weight summaries. We therefore report a null detection of sidereal-phase-lockedtransient coupling under the tested pipelines and provideconservative bounds on any timing-specific enhancement.
Jan-Frederik Flügge (2026) studied this question.