Symmetric Gaussian fits place two 2026 X-ray pulse centers of EXO 2030+375 near periastron

Do the clear 2026 outbursts of EXO 2030+375 occur near periastron after the recovery from its 2021 giant outburst? We fit fixed snapshots of public daily MAXI and Swift/BAT data with a constant background and a positive Gaussian pulse. We test all 22 orbit windows from February 2024 through October 2026 and preserve all failures. Using the Wilson et al. (2008) Fit 1 clock, the fitted July and October MAXI 2–20 keV pulse centers occur 1.4 and 1.3 days after periastron. Approximate 95% model ranges are 0.7–2.0 and 0.7–2.8 days. The 4–10 keV band gives similar times. Fermi/GBM pulse detections support the source identification. BAT does not give an accepted 2026 time. Pulse shape matters: wider asymmetric fits give peaks at 2.2 and 0.1 days. The October MAXI data end 3.5 days after periastron, so the full decay is not measured. The July window also has late flux outside the fitted pulse. Only two of six tested 2026 MAXI windows pass the timing cuts. These conditional measurements do not test the full forecast of an early shift between 2026 and 2031. The package preserves source data, hashes, code, the full orbit ledger, figures, uncertainty checks and offline reproduction instructions.

EXO 2030+375 · Be X-ray binary · orbital phase · X-ray monitoring · pulse timing · data coverage