A Search for Technosignatures Around 11,680 Stars with the Green Bank Telescope at 1.15–1.73 GHz
Authors: Margot Jean-Luc , Li Megan G. , Pinchuk Pavlo , Myhrvold Nathan , Lesyna Larry , Alcantara Lea E. , Andrakin Megan T. , Arunseangroj Jeth , Baclet Damien S. , Belk Madison H. , Bhadha Zerxes R. , Brandis Nicholas W. , Carey Robert E. , Cassar Harrison P. , Chava Sai S. , Chen Calvin , Chen James , Cheng Kellen T. , Cimbri Alessia , Cloutier Benjamin , Combitsis Jordan A. , Couvrette Kelly L. , Coy Brandon P. , Davis Kyle W. , Delcayre Antoine F. , Du Michelle R. , Feil Sarah E. , Fu Danning , Gilmore Travis J. , Grahill-Bland Emery , Iglesias Laura M. , Juneau Zoe , Karapetian Anthony G. , Karfakis George , Lambert Christopher T. , Lazbin Eric A. , Li Jian H. , Li Zhuofu (Chester) , Liskij Nicholas M. , Lopilato Anthony V. , Lu Darren J. , Ma Detao , Mathur Vedant , Minasyan Mary H. , Muller Maxwell K. , Nasielski Mark T. , Nguyen Janice T. , Nicholson Lorraine M. , Niemoeller Samantha , Ohri Divij , Padhye Atharva U. , Penmetcha Supreethi V. , Prakash Yugantar , Qi Xinyi (Cindy) , Rindt Liam , Sahu Vedant , Scally Joshua A. , Scott Zefyr , Seddon Trevor J. , Shohet Lara-Lynn V. , Sinha Anchal , Sinigiani Anthony E. , Song Jiuxu , Stice Spencer M. , Tabucol Nadine M. , Uplisashvili Andria , Vanga Krishna , Vazquez Amaury G. , Vetushko George , Villa Valeria , Vincent Maria , Waasdorp Ian J. , Wagaman Ian B. , Wang Amanda , Wight Jade C. , Wong Ella , Yamaguchi Natsuko , Zhang Zijin , Zhao Junyang , Lynch Ryan S. 
Published: October 2023

Abstract
We conducted a search for narrowband radio signals over four observing sessions in 2020–2023 with the L-band receiver (1.15–1.73 GHz) of the 100 m diameter Green Bank Telescope. We pointed the telescope in the directions of 62 TESS Objects of Interest, capturing radio emissions from a total of ∼11,680 stars and planetary systems in the ∼9′ beam of the telescope. All detections were either automatically rejected or visually inspected and confirmed to be of anthropogenic nature. We also quantified the end-to-end efficiency of radio SETI pipelines with a signal injection and recovery analysis. The UCLA SETI pipeline recovers 94.0% of the injected signals over the usable frequency range of the receiver and 98.7% of the injections when regions of dense radio frequency interference are excluded. In another pipeline that uses incoherent sums of 51 consecutive spectra, the recovery rate is ∼15 times smaller at ∼6%. The pipeline efficiency affects calculations of transmitter prevalence and SETI search volume. Accordingly, we developed an improved Drake figure of merit and a formalism to place upper limits on transmitter prevalence that take the pipeline efficiency and transmitter duty cycle into account. Based on our observations, we can state at the 95% confidence level that fewer than 6.6% of stars within 100 pc host a transmitter that is continuously transmitting a narrowband signal with an equivalent isotropic radiated power (EIRP) > 1013 W. For stars within 20,000 ly, the fraction of stars with detectable transmitters (EIRP > 5 × 1016 W) is at most 3 × 10−4. Finally, we showed that the UCLA SETI pipeline natively detects the signals detected with AI techniques by Ma et al.