SETI Narrowband Signal Searches Towards the Galactic Plane and Center

Two of the primary targets of the Breakthrough Listen program are the Galactic Center (GC) and a comprehensive blind survey of the entire Galactic Plane (GP) to search for artificial narrowband signals from ETIs. The line of sight toward the GC offers the largest integrated galactic star count of any direction in the sky, is a widely cited possible location for a beacon built by an advanced intelligence, and is the most energetic region in the Milky Way. Likewise, the GP is an ideal direction to search for such signals due to the increased likelihood that transmitters would emit toward this region as opposed to random directions. Here, I will discuss our observing and narrowband search strategy, as well as results from the Parkes Telescope, Green Bank Telescope, and Sardinia Radio Telescope for our GC Survey (0.7 – 93 GHz) so far. I will also discuss an extension of these strategies for our GP Parkes 21cm Multibeam Receiver Survey, covering two full scans of the GP. We employ a multibeam coincidence rejection technique used for Fast Radio Burst detection, which allows us to distinguish terrestrial interferences from truly sky-localized signals. In addition to our traditional narrowband search filters, we incorporate a machine learning filter in the form of a convolutional neural network to differentiate signals from false positives across the 13 beams, resulting in a significant reduction of detected candidates.