Breakthrough Listen Observations Of Interstellar Object 3I/ATLAS
The interstellar object 3I/ATLAS was discovered on July 1, 2025. There is currently no evidence to suggest that it is anything other than a natural astrophysical object. However, given the small number of such objects known (only three to date), and the plausibility of interstellar probes as a technosignature (a sign of extraterrestrial intelligence), (e.g. Freitas & Valdes 1985), thorough study is warranted (see Davenport et al. 2025).
The Breakthrough Listen Initiative, together with its network of collaborators, has undertaken observations of 3I/ATLAS using a variety of facilities worldwide, starting shortly after its discovery, and continuing through its closest approach to Earth. No technosignatures have been detected in any of these searches.
Observations of 3I/ATLAS using the Allen Telescope Array were undertaken in early July, 2025, within a few days of discovery. Data were acquired across frequencies of 1 – 9 GHz, reaching sensitivities between 10 – 110 W equivalent isotropic radiated power (EIRP). A publication reporting the results of the analysis has been submitted for peer review; a preprint is available here.
Astrobiology, SETI,
