Comets and Asteroids

A Search For Radio Technosignatures From Interstellar Object 3I/ATLAS With The Allen Telescope Array

By Keith Cowing

Status Report

astro-ph.EP

December 23, 2025

Filed under 3I/ATLAS, Allen Telescope Array, astro-ph.EP, astrogeology, astronomy, Comet, Doppler drift, icy world, Interstellar, NbeamAnalysis filtering, SETI Institute, Technosignatures

A Search For Radio Technosignatures From Interstellar Object 3I/ATLAS With The Allen Telescope Array — The distribution of the ∼ 74 million hits from this survey across drift rate. Note the peak of hits around 0 Hz/s (expected because most RFI transmitters are in the same reference frame as the telescope, i.e., on the ground). After the drift rate cut, the count of hits is much more even across the restricted drift rate range. Note that the sawtooth pattern seen across drift rate is a known artifact in the current development version of bliss, caused by an overestimation of SNR for high-bandwidth (≳ 10 Hz wide) hits close to integer multiples of the unit drift rate. It causes increased amounts of false positives close to these drift rates but does not cause false negatives (for more details, see Jacobson-Bell et al. 2025). — astro-ph.EP

In 2025 July, the third-ever interstellar object, 3I/ATLAS, was discovered on its ingress into the Solar System. Similar to the NASA Voyager missions sent in 1977, science probes by extraterrestrial life (artifact “technosignatures”) could be sent to explore other stellar systems like our own.

In this campaign, we used the SETI Institute’s Allen Telescope Array to observe 3I/ATLAS from 1–9~GHz. We detected nearly 74 million narrowband hits in 7.25~hr of data using the newly-developed search pipeline bliss.

We then applied blanking in frequency and drift rate to mitigate Radio Frequency Interference (RFI) in our dataset, narrowing the dataset down to ∼2 million hits. These hits were further filtered by the localization code NBeamAnalysis, and the remaining 211 hits were visually inspected in the time-frequency domain. We did not find any signals worthy of additional follow-up.

Accounting for the Doppler drift correction and given the non-detection, we are able to set an Effective Isotropic Radiated Power (EIRP) upper limit of 10−110~W on radio technosignatures from 3I/ATLAS across the frequency and drift rate ranges covered by our survey.

Sofia Z. Sheikh, Valeria Garcia Lopez, Isabel Gerrard, James R. A. Davenport, Wael Farah, Blayne Griffin, Steve Croft, Luigi F. Cruz, Imke de Pater, Ben Jacobson-Bell, Mark Masters, Karen I. Perez, Alexander W. Pollak, Carol Shumaker, Andrew Siemion

Comments: Submitted to AAS Journals
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Popular Physics (physics.pop-ph)
Cite as: arXiv:2512.18142 [astro-ph.EP] (or arXiv:2512.18142v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2512.18142
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Submission history
From: Sofia Sheikh
[v1] Fri, 19 Dec 2025 23:51:12 UTC (569 KB)
https://arxiv.org/abs/2512.18142

Astrobiology, SETI,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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