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

A constant period fits eleven average Swift/BAT eclipse centers of 4U 1700-37 from 2005 to 2026

A constant period fits eleven average hard X-ray eclipse centers of 4U 1700-37. We measure eleven mean eclipse profiles in a frozen public Swift/BAT 15–50 keV data file. We retain 85,262 pointings from February 2005 to October 2026. The center is the midpoint of the two half-amplitude crossings of a model with separate ingress and egress widths. Five-cycle block resamples give the center errors. A constant period of 3.4116365 ± 0.0000048 days fits the centers (chi square 3.73 for 9 degrees of freedom). The fractional period derivative is (+0.28 ± 4.52) × 10⁻⁷ yr⁻¹. Thus these data alone do not resolve a period change. Changes in the profile window, weights, and center definition shift some centers by more than their resample errors. Fits that add older published times depend on the assumed offset between center definitions. The quoted errors are conditional on the profile and block choices. The package contains the frozen input, new time tables, resamples, source code, and figures. It supplies a clock test and data for further tests; it does not establish physical orbital decay.

4U 1700-37 · Swift BAT · eclipse timing · orbital period · orbital decay · X-ray binaries · block bootstrap · public data · eclipse profiles · center definition

Admitted 2 citing publications

References

7
  1. usesdoi:10.1093/mnras/stw1299

    We use the 24 printed eclipse times and revised errors in Table 1 to reconstruct the old clocks.

  2. usesdoi:10.1088/0067-0049/209/1/14

    We use public Swift/BAT transient monitor data and cite the monitor description.

  3. doi:10.1051/0004-6361/201425191
  4. doi:10.1093/mnras/staa437
  5. doi:10.1016/j.jheap.2026.100567
  6. usesdoi:10.3847/1538-4357/ac7c74

    We use Astropy for FITS data and astronomical time calculations.

  7. usesdoi:10.1038/s41592-019-0686-2

    We use SciPy for profile fits and statistical calculations.

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