Dear friends,
I am writing from the 237th meeting of the American Astronomical Society, which is taking place in hundreds of home offices this year due to the COVID-19 pandemic. I presented the results of our 2018-2019 search in the Astrobiology session on Tuesday afternoon to about 75 attendees. One of the attendees was Larry Lesyna, who has been a steadfast supporter of the UCLA SETI Group since its inception. I am thrilled to report that Larry made another generous gift to enable additional observations with the Green Bank Telescope. Larry was involved in the early SETI efforts at NASA and has been advocating for the inclusion of SETI in the university curriculum. He has described the benefits that humanity could gain from detecting a message from another civilization in a white paper submitted to the Astro2020 decadal survey. He was also featured in one of the first UCLA SETI Group newsletters.
It was challenging to give an overview of our results, which are now published in the Astronomical Journal, in less than 10 minutes. You can view a prerecorded version of my talk here (9-minute video, 24 MB). One of the audience questions conveyed through the Slack platform had to do with the definition of a candidate detection and whether we define a detection in the same way as a recent Breakthrough Listen (BL) survey by Price et al. 2020 (Figure 1). Indeed, their team and ours used the same signal-to-noise threshold (10 times the standard deviation of the noise), frequency resolution (3 Hz), telescope (Green Bank Telescope), and the same region of the spectrum (approximately 1-2 GHz) in this comparison. Our team used two scans of 150 seconds whereas Price et al. 2020 used three scans of 300 seconds. The difference in the number of signals detected per hour of telescope time is due to a combination of factors, with the end-to-end sensitivities of the data processing pipelines and signal detection algorithms each contributing about a factor of 10.
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Figure 1: Number of candidate signals detected in recent searches published by the UCLA SETI Group and BL.
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In a previous newsletter, I mentioned an intriguing signal first reported by UCLA physics undergraduate student Nadine Tabucol in the direction of WASP-49. After additional analysis, we determined that the signal is anthropogenic (Figure 2). You can see Nadine's signal drifting in frequency in both of our scans of WASP-49 (two grey panels). The signal was initially not detected in any other direction on the sky (30 dark panels). However, when we analyzed the full data set, we detected the signal in another direction on the sky (bottom left panel), which rules it out as being extraterrestrial. This signal is the closest our group has come to detecting an extraterrestrial technosignature.
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Figure 2: Dynamic spectra (aka spectrograms) showing the time-frequency structure of a signal spotted by Nadine Tabucol in the direction of WASP-49. Time in seconds increases downward and frequency in Hertz increases toward the right.
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You may have read news reports of a possible detection by the BL team. They have detected a signal that is observed in only one direction on the sky in a set of observations that was not optimized for a SETI detection. Consistent with the principles outlined in the Declaration of Principles Concerning the Conduct of the Search for Extraterrestrial Intelligence, we have offered our assistance in running their data through our pipeline.
The graduate school application season is in full swing. Forty-two students expressed interest in the Ph.D. position available in the UCLA SETI Group. Admission committees are reviewing the applications and offers will be made soon. Applicants have until April 15, 2021 to make a decision.
I hope you are healthy and safe.
Warm regards,
Jean-Luc Margot
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