Block noise tests do not confirm a fixed 19.1365-day component in 2014–2026 BAT and MAXI data for 4U 2206+54
We test whether later public X-ray data for 4U 2206+54 contain a fixed 19-day component in addition to its 9.6-day harmonic. A two-harmonic fit to BAT data before 2014 selects a reference period of 19.136521121 days. We then test BAT 15–50 keV and MAXI 4–10 keV data separately in 2014–2019 and 2020–2026. The model has 180-day intercepts and weights that include a fixed variance term. The variance term uses each full band record, so the date split is not fully blind. Random sign tests use 40-, 80-, and 160-day calendar blocks and 10000 draws. All four primary comparisons fail a 0.05 threshold after correction for four tests under each block choice. The smallest adjusted p value is 0.0808. The largest conditional 95% amplitude bounds across the block choices are 0.0003025 and 0.0004256 count cm^-2 s^-1 for BAT, and 0.002065 and 0.002676 photon cm^-2 s^-1 for MAXI, in the two later eras. These bounds are not simultaneous and exclude period and calibration uncertainty. Secondary energy bands give different results and have calibration limits. The tests do not establish signal absence, a period change, or an orbital period. The package preserves the frozen inputs, provenance, code, figures, numerical controls, and a clean reproduction check.
4U 2206+54 · BD +53 2790 · Swift BAT · MAXI · X-ray binary · orbital modulation · harmonic · block bootstrap · public data · reproducible research
References
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This paper reported the 19-day BAT modulation and changes relative to the 9.6-day ASM modulation.
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This paper reported both shorter and longer ASM modulation peaks.
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We use twice its 9.5591-day ASM period in an exploratory clock check.
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We use twice its 9.568-day optical period in an exploratory clock check.
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We use twice its 9.55346-day fitted optical period in a disclosed post-analysis sensitivity check.
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We use the public Swift/BAT transient monitor daily data described by this paper.
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We use public daily light curves from the MAXI mission described by this paper.
- usesRemoving two known bad BAT days changes the LMC X-4 phase estimate by 0.034 cycles in a weighted daily test sci:sha256:d152ecc67c93e86a6bf741b8e9e67a6acae54dad161b2f67cd427e136b1ddd4f
We apply the external BAT exclusion for MJD 58571 and 58572. This study shows its effect for a different source. We use no code or numeric data from its package.
Cited by
2 publicationsPublic catalog entries on Sciscape.
- usesBlock noise tests support a 9.6-day signal in 2014–2026 BAT and MAXI data for 4U 2206+54
We extend its long-component study with short-component tests and a shared-sign joint search. We use the same era boundaries, slow offsets, weight rule, and block lengths, with an independent code implementation. The numeric input hashes match.
- usesBlock noise tests do not show a 9.6-day period change between 2014–2019 and 2020–2026 for 4U 2206+54
Its descriptive short-period scans motivate this test. We use its source choice, era boundaries, data quality rule, and 180-day intercept form. We add a searched common-versus-separate frequency test and conditional resolution trials. The public observations overlap.