Clustered nulls reduce the evidence for a 629-day planetary clock in GLEs and X-class flares to p of 0.004 to 0.3; cycle 25 (2019-2026) events lean to the predicted phase but do not confirm it

Stefani et al. (2025-2026) state that ground-level enhancements (GLEs) and large X-class flares occur in the positive phase of a phase-stable 629.29-day beat of planetary tides. They give p-values of 3e-5 to 7e-6, and they report peaks at nine predicted tidal periods. Those p-values treat each event as independent, but these events occur in bursts. Also, the period was first found in the same GLE data. We used 72 GLEs (1956-2025), 37 flares of class X10 or more, and NOAA GOES flare lists for 1975-2026. A 0.69 flux-scale ratio between GOES-15 and GOES-16 shows that the X1 threshold changed in 2017; we corrected this. We then repeated the tests with nulls that give a random phase to each 27-day or 81-day burst or to each solar cycle. We reproduce the published phases (2.04, 2.96 and 2.58 rad against 2.01, 2.96 and 2.58). With clustered nulls, the fixed-period p-values become 0.024-0.051 for GLEs and 0.07-0.31 for X1+ flares. After a search of the 450-900 day band, no set has p < 0.05. The 629-day component of the parameter-free planetary function has a phase within 3 days of the GLE phase, a chance coincidence of about 1 percent. The GLE V-test against that phase gives p = 0.004 for 27-day bursts. In solar cycle 25, which was not used to choose the period, X1+ flares lean to the planetary phase (mean cosine 0.35-0.38, p about 0.05). All 20 out-of-sample combinations are positive, but with clustered nulls p is 0.03-0.34. Five cycle-25 GLEs give p = 0.22. The seven new predicted periods do no better than random periods (p = 0.08-0.24). Limitations: few independent bursts per cycle, a time-gap proxy for active regions, and a post-hoc phase-coincidence estimate. Cycle 26 can give a decisive test.

solar flares · ground-level enhancement · quasi-biennial oscillation · Rieger periodicity · planetary tides · Rayleigh test · event clustering · GOES XRS · out-of-sample test · solar cycle 25 · magneto-Rossby waves