Search for Muon Excess from GRB 221009A in Data from the GRAPES-3 Muon Telescope

GRB 221009A was the most energetic gamma-ray burst (GRB) ever recorded, with photon energies exceeding 10~TeV. Ground-based detectors such as LHAASO and Carpet-2 reported delayed ultra-high-energy photon events, and the Yangbajing muon telescope observed a coincident enhancement in ground-level muons, raising interest in secondary particle production in the atmosphere. In this study, we analyzed 1-minute muon counting data from the GRAPES-3 muon telescope in Ooty, India, which was located at a zenith angle of about 11degree with respect to the GRB direction at the time of the burst on October 9, 2022. Data from all 16 detector modules were summed and divided into nine angular sectors to search for directional excesses. After applying pressure correction, we found no statistically significant deviation in any direction. This null result provides an independent constraint on GRB-induced atmospheric muon production and highlights the importance of high-precision, multi-directional observations for evaluating such rare transients. Future studies will benefit from detailed simulations of detector responses to high-energy atmospheric cascades.