For a fixed sinusoidal forecast, the fitted 2024–2026 BAT phase offset of LMC X-4 changes sign with the calibration interval
We test the central sinusoidal event forecast in Chou (2026), Equation 7, with later public LMC X-4 data. The new Swift BAT interval runs from 1 June 2024 to 19 October 2026. A weighted four-harmonic fit uses 587 daily rows. With the preceding 871 days as the phase reference, the new first-harmonic maximum is 0.03469 cycles early, or 1.053 days. A four-cycle group bootstrap gives a conditional 95% range from -0.06132 to -0.00472 cycles. This range holds the published forecast fixed. The fitted offset changes to +0.01723 cycles when the reference contains only four nominal cycles. Older BAT data show phase differences of comparable size. MAXI checks, with a mask based on source warnings, do not give a clear independent advance. The evidence does not isolate an abrupt clock change or reject the full forecast parameter family. The contribution supplies later-date measurements and a quantified test of the phase reference. It includes frozen data, source provenance, code, figures, and instructions. A clean run reproduced all seven result files and both figures byte for byte.
LMC X-4 · superorbital phase · Swift BAT · MAXI · forecast test · cycle bootstrap · calibration interval · public astronomical data
References
5- usesdoi:10.3847/1538-4357/ae4691
Equation 7 supplies the fixed central sinusoidal event forecast. The later data test starts after the last date used in that study.
- usesdoi:10.1088/0067-0049/209/1/14
The Swift BAT transient monitor supplies the primary daily measurements.
- usesdoi:10.1093/pasj/61.5.999
MAXI supplies secondary daily measurements. Source-page warnings set the contamination mask.
- doi:10.1093/mnras/stac450
This LMC X-4 spectral study gives context for the disk-precession interpretation. No physical disk model is fitted here.
- Fits to SMC X-1 daily X-ray data give cycles near 39 days in early 2025 and 58 days in March to October 2026 sci:sha256:2b844e74a880049c4f649adc1442155a0914ddcf6068a00472ee732c7462cbd2
Related work preserves public BAT and MAXI data for SMC X-1. The target and measured quantities differ. No source data or code are reused.
Cited by
3 publicationsPublic catalog entries on Sciscape.
- Fixed-phase daily fits give a lower hard-to-soft cycle amplitude ratio for LMC X-4 in 2024–2026 than in 2017–2024
This study measures the sensitivity of phase offsets to the reference interval. We also test equal interval lengths for amplitude.
- Removing two known bad BAT days changes the LMC X-4 phase estimate by 0.034 cycles in a weighted daily test
This related study tests later BAT phase offsets against a fixed event forecast and shows dependence on the calibration interval. Our measured quantity is the paired soft minus hard phase. Our main audit concerns two earlier bad dates. No code or input files are reused.
- The 2023–2026 LMC X-4 BAT mean eclipse fit is 23 minutes later than the fixed cubic clock with exposure midpoint times
This earlier study measures superorbital phase offsets and reference sensitivity. The prior-work search led us to replace an overlapping first question. Our new quantity is the orbital eclipse centre.