12-20 July 2017
Asia/Seoul timezone
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[SH030] Cosmic ray "short burst" observed with the GMDN in June 2015


  • Kazuoki MUNAKATA

Primary authors



The GRAPES-3, a large muon tracking detector experiment in India, reported recently a short "burst" of cosmic ray intensity observed lasting about one hour in June 22, 2015 in association with a large geomagnetic storm following the arrival of an interplanetary shock at the Earth (Mohanty et al., Physical Review Lett., 117, 2016). In the present paper, we analyze this event observed with the Global Muon Detector Network (GMDN) consisting of four multi-directional muon detectors and derive the cosmic ray anisotropy vector every one minute from the best-fitting analyses of the data observed in a total of sixty directional channels available from the GMDN. We find a clear rotation of the anisotropy vector during the period when the "burst" was observed. According to this rotation, the anisotropy orientation entered the field of view of the muon detector and was observed as the cosmic ray "burst". We will discuss the physical origin of this anisotropy rotation, also referring to the in-situ measurements of the IMF and solar wind.