The Breakthrough Listen Search for Intelligent Life: Observations of 1327 Nearby Stars Over 1.10-3.45GHz

Breakthrough Listen (BL) is a 10 year initiative to search for signatures of technologically capable life beyond Earth via radio and optical observations of the local universe. A core part of the BL program is a comprehensive survey of 1702 nearby stars at radio wavelengths (1-10 GHz). Here, we report on observations with the 64 m CSIRO Parkes radio telescope in New South Wales, Australia, and the 100 m Robert C. Byrd Green Bank radio telescope in West Virginia, USA. Over 2016 January to 2019 March, a sample of 1138 stars was observed at Green Bank using the 1.10-1.90 GHz and 1.80-2.80 GHz receivers, and 189 stars were observed with Parkes over 2.60-3.45 GHz. We searched these data for the presence of engineered signals with Doppler-acceleration drift rates between +/- 4Hz s(-1). Here, we detail our data analysis techniques and provide examples of detected events. After excluding events with characteristics consistent with terrestrial radio interference, we are left with zero candidates. That is, we find no evidence of putative radio transmitters above 2.1 x 10(12) W, and 9.1 x 10(12) W for Green Bank and Parkes observations, respectively. These observations constitute the most comprehensive search over 1.10-3.45 GHz for technosignatures to date. All data products, totaling similar to 219 TB, are available for download as part of the first BL data release (DR1), as described in a companion paper.