GRB 221009A observations with LST-1 at VHE gamma rays

On October 9th, 2022, the brightest gamma-ray burst (GRB) since the first GRB observation in the late sixties was detected by the Fermi-GBM and Swift-BAT telescopes (GRB 221009A). The outstanding characteristics of this GRB triggered extensive follow-up observations of the source across all wavebands, including at very-high-energy (VHE) gamma rays with the Large-Sized Telescope prototype (LST-1) of the upcoming Cherenkov Telescope Array Observatory (CTAO). In this contribution, we present the analysis and results of the LST-1 observation campaign in October 2022, focusing on the data taken under nominal observing conditions and above 200 GeV. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License