This quarter, I am teaching the 9th edition of the UCLA SETI course. We were fortunate to obtain time on the Green Bank Telescope and to conduct 32 additional observations on April 18, 2024. Students were able to connect to our Zoom session to witness the operation of the telescope and to learn from our observatory friend, Dr. Ryan Lynch. Some of the most dedicated classifiers on arewealone.earth were also able to join us. Approximately 3,000 of the most promising signals from our 2024 data have been uploaded to the Zooniverse platform, giving project volunteers the opportunity to analyze data that no one has carefully examined yet.
Our observing sequence follows an ABAB pattern that I have not previously described in detail. In an ABAB pattern, we point the telescope at our first source (A) and record data for 150 seconds, then we go to the second source (B) and record data for 150 seconds. We then repeat the A and B scans once and then move on to the next pair of sources. This observing sequence is quite advantageous in that it allows us to effortlessly identify 99.5% of the radio frequency interference (RFI) in our data. It is remarkably effective because an extraterrestrial signal would be detected only in the main lobe of the antenna beam pattern in the direction of source A or the direction of source B, but not both. Any signal that is detected in both directions A and B is emitted locally and can be eliminated. These signals often reach the receiver through one of the multiple sidelobes of the antenna beam pattern (Figure 1).
The antenna beam pattern of the Green Bank Telescope at a frequency of 1.4 GHz. The plot
shows the antenna gain in decibels compared to an isotropic antenna, as a function of angle from the boresight direction. Note the ~30 dB (factor of 1000) difference between the main lobe and the first sidelobe (Boothroyd et al. 2011).
An example signal that is detected in both scans of source A (top and bottom) but also in a scan of source B (middle), indicating RFI. Time (s) is on the vertical axis and frequency (Hz) is on the horizontal axis.
As in previous years, students practiced the detection of technosignatures by computing Fast Fourier Transforms and searching for the Voyager 1 signal in archival data. They are now searching for candidate technosignatures in our April 18, 2024 data. At the same time, they are working on software development in small teams, continuing the virtuous cycle of adding new capabilities to our data-processing pipeline. I am really excited about the projects that they are working on!
In March, UCLA graduate student Megan Li and I spoke remotely about UCLA SETI efforts at a conference titled Interstellar Frontiers: Bridging SETI, Astrobiology, and the SKA. Our talks are archived online – here are links to Megan's talk and my talk. Megan passed her qualifying exam and is busy designing and training an AI tool to automatically identify RFI in our data. Her preliminary results are encouraging and I look forward to testing the final product.
I was unable to attend this year's Drake Awards ceremony organized by the SETI Institute due to university duties, but Megan attended and was tickled to be seated next to Dr. Jill Tarter. This year's Drake Award winner, Dr. Andrew Siemion, has had a tremendous impact on the SETI field and the genesis of UCLA SETI. We used his excellent 2013 paper as a blueprint for developing the first version of the UCLA SETI pipeline back in 2016. Congratulations, Andrew!
