Commensal Targeted Search and Blind Survey in the Search for Extraterrestrial Intelligence at the Allen Telescope Array

The SETI Institute is a world leader in the Search for Extraterrestrial Intelligence (SETI) with a dedicated cm-wave interferometer array designed especially for SETI, called the Allen Telescope Array. Here we describe a new system which performs an imaging survey for anomalous (narrow band ~ 100 kHz, repeating ~ 1 microsec, short duration ~ 10s) signals that may be indicative of extraterrestrial communication or an unexpected astronomical phenomenon. This imaging survey is performed commensally with a targeted SETI search focusing on individual stars. The application of existing ATA imagers (correlators) here is a prototype for future SETI. Because of the inherent effectiveness of imaging surveys over targeted surveys when using interferometer telescopes, we believe the technology developed here will pave the way for high-efficiency SETI at future large radio telescopes, such as the Square Kilometer Array.