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astro-ph.HE · High Energy Astrophysical Phenomenaastro-ph.IM · Instrumentation and Methods for Astrophysics

Selected 4–10 keV MAXI eclipse centers allow zero drift from the 2019 SMC X-1 model in 2019–2026 under block resampling

We measure eclipse centers in public MAXI scans of SMC X-1 after the Hu 2019 data interval. The test covers 23 March 2019 to 20 October 2026. We select bright orbits with data outside eclipse. We fit separate ingress and egress transitions in eight intervals. The 4–10 keV drift relative to the 2019 model is -1.47 minutes/year. A 60-day block bootstrap gives an empirical 95% interval of [-4.37, +1.69] minutes/year. This interval includes zero. A constant difference between the flux center and the orbit epoch is free. The package includes other energy bands and tests of selection, weights, shape, and block length. The 2–4 keV drift interval excludes zero with all eight intervals. It includes zero when the final interval is removed. The errors assume that the sampled blocks describe the main short-term correlations. They exclude unknown slow changes in shape or calibration. The result does not prove that the orbit model is exact. The contribution is a later timing table, a time-system audit, and a complete reproduction package. It preserves the frozen scan data, source addresses, code, fit samples, checks, and figures.

SMC X-1 · MAXI · X-ray binaries · eclipses · orbital ephemeris · public data · time systems

Admitted 2 citing publications

References

11
  1. usesdoi:10.3847/1538-4357/ab48e4

    The fixed orbit coefficients and last input date define the main test.

  2. usesdoi:10.1051/0004-6361/201425191

    The older coefficients define the comparison model.

  3. usesdoi:10.1093/pasj/61.5.999

    The public MAXI data are the measurement source.

  4. Standard and basic MAXI products show lower SMC X-1 flux outside eclipse in February 2026 sci:sha256:ba58c453d566f7d234feb876b48ec20a3b79f608070d349cae1d1b0ea78db8af

    This prior MAXI flux study uses an assumed eclipse cut. It also explains the time products.

  5. Dates are one day late in four of six tested Swift/BAT pointing tables for 2023–2025 sci:sha256:8df335c8aba52a813960ed565c10e06026b400e9f6d21ae623aefa7ad652b251

    This separate Swift/BAT date-field audit includes SMC X-1 as an unaffected control. It does not test the MAXI inputs.

  6. doi:10.3847/1538-4357/ac4d24

    Earlier NuSTAR eclipse constraints end before the main interval.

  7. doi:10.3847/1538-4357/ae1ca6

    The later NinjaSat study applies a local epoch change.

  8. doi:10.48550/arXiv.2605.21294

    Recent optical work adopts the 2019 orbit model.

  9. doi:10.1051/0004-6361/202449355

    The later soft X-ray ingress test has no egress coverage and gives no new orbit constraint.

  10. doi:10.1051/0004-6361/202450937

    The 2023 IXPE observations use the 2019 orbit model and show a dip before eclipse.

  11. doi:10.48550/arXiv.2507.13515

    The recent review lists SMC X-1 eclipse timing data through 2018.

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