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astro-ph.IM · Instrumentation and Methods for Astrophysicsastro-ph.HE · High Energy Astrophysical Phenomena

A local frequency balance test flags five of eight listed Crab glitches in the 2010–2026 monthly record

Adjacent monthly timing fits give a local test for sudden changes in the rotation of the Crab pulsar. We subtract the frequency change predicted by the two endpoint derivatives from the observed frequency change. We calculate this balance for 481 adjacent intervals in 482 public Jodrell Bank solutions from May 1988 to July 2026. We match 27 catalog events. A reference level of 34.45 nHz is the higher 99th percentile of absolute balances in 178 background intervals before 2010. It flags five of eight listed events in 2010–2026. The two listed 2025 events give 33.44 and 31.45 nHz and remain below this level. There is one positive and one negative flag among 169 later background intervals. Mask and percentile changes give five to seven event flags. Quoted fit errors do not give the observed balance scale. The absolute values of 69 of 169 later background balances exceed five times an upper bound on the formal standard deviation. The two positive background flags in the full record occur during known 1997 and 2011 radio propagation events. These time matches do not establish a cause. The catalog and monthly fits share observations, and some fit rules use known glitches. Thus this is a retrospective benchmark, not a blind detection test or a measurement of instantaneous glitch size. We preserve numeric data, source hashes, code, figures, all interval labels, and offline reproduction steps.

Crab pulsar · pulsar timing · glitches · timing noise · frequency balance · public data · radio propagation · reproducible benchmark

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References

10
  1. usesA curved Crab spin-down baseline reduces errors in 37 later records under a fixed early fit sci:sha256:9c5a7aeba6f8d6be34e93c9d9c0f8854fd608ba130002c481b837a45f268973e

    We use this publication’s numeric extraction for a separate check on all 482 frequencies, derivatives, and quoted errors. We do not reuse its fitted models.

  2. usesdoi:10.1093/mnras/265.4.1003

    This paper describes the origin of the public Jodrell Bank Crab timing data. We use its monthly data resource and give the source URL and snapshot hash.

  3. usesdoi:10.1093/mnras/stab3336

    This paper describes the Jodrell Bank Glitch Catalogue. We use the current captured numeric Crab entries as reference labels.

  4. doi:10.1093/mnras/stu395

    This prior study used daily observations and an automated detector to study small Crab glitches. Its physical sensitivity result does not transfer directly to monthly fits.

  5. doi:10.1046/j.1365-8711.2003.06825.x

    This paper studies Crab timing noise and provides context for the formal-error assessment.

  6. doi:10.3847/0004-637X/826/2/187

    This paper proposes an additional small 2006 Crab event. It shows why absence from the reference catalog is not proof of no event.

  7. doi:10.1093/mnras/sty1294

    This paper reports a delayed rise in the large 2017 Crab glitch. It gives context for limits of a monthly local balance.

  8. doi:10.1111/j.1365-2966.2010.17459.x

    This paper studies the 1997 Crab radio propagation event, which occurs in one flagged background interval.

  9. usesdoi:10.1109/MCSE.2007.55

    Matplotlib makes the publication figures.

  10. usesdoi:10.1038/s41586-020-2649-2

    NumPy performs array calculations and empirical quantiles.

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