Monitoring the upper atmospheric temperature and the interplanetary magnetic field with the GRAPES-3 muon telescope .

by Mr Surojit Pal (DHEP, TIFR)

Thursday 14 Aug 2025, 11:00 → 13:00 Asia/Kolkata

DAA A-269 (TIFR, Mumbai )

In this talk I will present the influence of upper atmospheric temperature and interplanetary magnetic field (IMF) variations on the cosmic ray muon flux measured by the GRAPES-3 muon telescope over 22 years (2001–2022), covering a complete solar magnetic cycle. We developed an automated, algorithmic method, which employs Bayesian blocks to discretize the data stream into periods and exploits the correlations among the sixteen independent modules of the muon telescope to distinguish instrumental effects from physical variations. After correcting for detector efficiency, we found that the muon flux is anti-correlated with both upper atmospheric temperature and IMF with a temperature coefficient 𝝰_𝗧 = - 0.23 ± 0.02 %K^-1 and a magnetic field coefficient 𝛄_𝐌  = - 0.57 ± 0.03 %nT^-1. These results show that GRAPES-3 is sensitive to both atmospheric and solar effects and highlights its effectiveness for long term monitoring of the upper atmosphere and weather in space.