GW240925 and GW250207: Astrophysical Calibration of Gravitational Wave Detectors

Authors

• A. G. Abac, Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut)
• I. Abouelfettouh, LIGO Hanford
• F. Acernese, Università degli Studi di Salerno
• Teviet Creighton, The University of Texas Rio Grande ValleyFollow
• Mario C. Diaz, The University of Texas Rio Grande ValleyFollow
• Raul Alberto Espinosa Perez, The University of Texas Rio Grande Valley
• J. Lawrence, The University of Texas Rio Grande Valley
• Francisco Llamas Villarreal, The University of Texas Rio Grande Valley
• Soma Mukherjee, The University of Texas Rio Grande ValleyFollow
• Gaukhar Nurbek, The University of Texas Rio Grande ValleyFollow
• Volker Quetschke, The University of Texas Rio Grande ValleyFollow
• Miriam Ramos Arevalo, The University of Texas Rio Grande ValleyFollow
• Wenhui Wang, The University of Texas Rio Grande Valley

Document Type

Article

Publication Date

8-13-2026

Abstract

GW240925 and GW250207 are two loud gravitational-wave signals from binary black hole coalescences observed with network signal-to-noise ratios ∼32 and ∼69, respectively, by the LIGO Hanford-LIGO Livingston-Virgo network. Gravitational-wave signals from coalescing binaries have characteristic phase and amplitude evolution predicted by general relativity. These signal waveforms, together with measured instrumental calibration uncertainties, are used to infer source parameters. However, for sufficiently loud detections, it is possible to constrain the calibration of the detectors directly using the signals themselves. We present the first informative astrophysical measurements of gravitational-wave detector calibration. For GW240925, we verify the inference of Hanford calibration from the astrophysical signal through cross-checks with known calibration errors obtained from in situ measurements. At the time of GW250207, the Hanford detector was not fully stabilized, leading to elevated calibration uncertainties; thus, astrophysical calibration is essential to obtain accurate data and to enable source localization. These well-localized, high signal-to-noise observations have the potential to offer precise measurements of source properties, stringent tests of general relativity, and informative dark siren measurements, provided that calibration uncertainties are properly incorporated. As detector sensitivity improves, astrophysical calibration will become an increasingly valuable complement to in situ calibration measurements. Obtaining accurate calibration will be essential for precision gravitational-wave science.

Comments

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Recommended Citation

Abac, A. G., I. Abouelfettouh, F. Acernese, et al. “GW240925 and GW250207: Astrophysical Calibration of Gravitational Wave Detectors.” Physical Review Letters 137, no. 7 (2026): 071401. https://doi.org/10.1103/gzrj-mwv3.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Publication Title

Physical Review Letters

DOI

https://doi.org/10.1103/gzrj-mwv3