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A Search for Extraterrestrial Technosignatures in Archival FAST Survey Data Using a New Procedure

By Keith Cowing
Status Report
May 29, 2023
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A Search for Extraterrestrial Technosignatures in Archival FAST Survey Data Using a New Procedure
The frequency–time plane showing candidate clusters which are detected by DBSCAN and pass the selection criteria of candidates. Candidates of real observational data are marked in black, and birdies are marked in red. The background shows a randomly drawn sample (∼ 1/1000 of all) of the raw observational data, since the raw data is too large to be plotted simultaneously. Note that each dot consists of a cluster (or even several clusters) of hits, but the distances between them are too small to be resolved in this figure. — astro-ph.IM

The aim of “search for extraterrestrial intelligence” (SETI) commensal surveys is to scan the sky to find possible technosignatures from the extraterrestrial intelligence (ETI).

The mitigation of radio frequency interference (RFI) is the important step for the search, especially for the most sensitive Five-hundred-meter Aperture Spherical radio Telescope (FAST), which can detect more weak RFI. In this paper, we propose our procedure of RFI mitigation using several new methods, and use the procedure to perform a search for ETI signals from the data of FAST’s first SETI commensal sky survey.

We detect the persistent narrowband RFI by setting a threshold of the signals’ sky separation, and detect the drifting RFI (and potentially other types of RFI) using the Hough transform method. We also use the clustering algorithms to remove more RFI and select candidates. The results of our procedure are compared to the earlier work on the same FAST data. We find that our methods, though relatively simpler in computation, remove more RFI, but preserve the simulated ETI signals except those severely affected by the RFI.

We also report more interesting candidate signals, about a dozen of which are new candidates that are not previously reported. In addition, we find that the proposed Hough transform method, with suitable parameters, also has the potential to remove the broadband RFI.

We conclude that our methods can effectively remove the vast majority of the RFI while preserving and finding the candidate signals that we are interested in.

Yu-Chen Wang, Zhen-Zhao Tao, Zhi-Song Zhang, Cheqiu Lyu, Tingting Zhang, Tong-Jie Zhang, Dan Werthimer

Comments: 13 pages, 10 figures, submitted to AJ. We explore new techniques including the Hough transform to remove more RFI for the FAST SETI surveys
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Popular Physics (physics.pop-ph)
Cite as: arXiv:2305.16356 [astro-ph.IM] (or arXiv:2305.16356v1 [astro-ph.IM] for this version)
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Submission history
From: Yu-Chen Wang
[v1] Thu, 25 May 2023 05:32:17 UTC (879 KB)
Astrobiology, SETI,

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) 🖖🏻