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astro-ph.IM · Instrumentation and Methods for Astrophysicsastro-ph.SR · Solar and Stellar Astrophysics

Heliocentric times shift the J2130 period derivative by −0.74 × 10⁻¹² s/s in 2018–2025 ZTF fits with stable profiles

We measure the effect of time convention on a photometric clock fit for the known binary ZTF J213056.71+442046.5. A fixed ZTF DR24 response supplies 2,465 selected g and r measurements from 2018–2025. The main model has separate six-harmonic filter profiles, filter/year means, and a shared quadratic phase clock. Midpoint BJD TDB gives a period derivative of (−3.067 ± 0.422) × 10⁻¹² s/s, with one statistical standard error from groups of observations on the same UTC date. Archive HJD UTC gives −3.810 × 10⁻¹² s/s. The shift is −0.742748 × 10⁻¹² s/s. A constant-period injection at the actual times acquires −0.743006 × 10⁻¹² s/s when fitted in HJD. The solar-system origin change supplies almost all of the effect; changing UTC to TDB alone has little effect here. The shift remains near −0.743 × 10⁻¹² s/s for four tested harmonic orders. Fits trained through 2022 reduce later 2023–2025 loss by 30.0% when they permit a decreasing period. Later means are refitted, while the clocks and profiles stay fixed. The absolute derivative depends on profile choice. The result does not establish excess physical decay or a new planet. Earlier papers already measured decay. This work adds a sample-specific time-convention test, a retrospective prediction check, and a package with raw data, source records, code, results, and figures.

ZTF J213056.71+442046.5 · ZTF DR24 · heliocentric Julian date · barycentric Julian date · period derivative · time standards · hot subdwarf binary · public astronomical data · reproducible analysis

Admitted 2 citing publications

References

9
  1. usesdoi:10.26131/IRSA598

    The analysis uses one frozen ZTF DR24 light-curve response. The data DOI identifies the archive product. The exact release, query, response, and hash are preserved.

  2. usesdoi:10.1088/1538-3873/aae8ac

    This paper describes the ZTF data processing, products, and archive.

  3. usesdoi:10.1093/mnras/stac3492

    This paper supplies the target context, an earlier null decay result, and the numerical reference period. Our frequency correction and curvature remain free.

  4. doi:10.1134/S1063773724700543

    This earlier work measured decay with ZTF and RC600 observations. Our ZTF data overlap its survey sample, so the data are not independent. We do not claim the first decay detection.

  5. doi:10.1051/0004-6361/202659317

    This earlier work measured a precise derivative with fast photometry. It supplies the comparison value and limits any claim that the archive fit gives new physical decay evidence.

  6. supportsdoi:10.1086/655938

    This paper explains why time origin and time scale must both be stated. Our result quantifies their effect for this target, sample, and clock model.

  7. usesdoi:10.3847/1538-4357/ac7c74

    Astropy supplies time-scale conversion and geometric arrival-time corrections. The package records exact software and time-data versions.

  8. usesA decreasing period improves 2023–2025 ZTF predictions for J0651 with fixed light-curve models sci:sha256:f28e4c51025af003207eca6188ae8a9b638eed1f05c1444fb2b92772006b511e

    We use its earlier-fit/later-data test design for survey clocks. The J2130 code is new. Our later filter/year means are refitted for both clocks.

  9. usesA decreasing period improves 2024–2025 ZTF predictions for J1539 with fixed flux profiles sci:sha256:99a28d7b138c66ef2e4c00ca666445d4993dfbf9f8aac2545c4ffab8fcf3ed47

    This related J1539 study supplies method context for fixed-profile predictions and time-block checks. We do not reuse its data or source code.

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