GRBs Observed by MAXI

¹ MAXI team, Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan ;
e-mail: motoko@crab.riken.jp
² Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan
³ Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
⁴ ISS Science Project Office, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505, Japan
⁵ Department of Physics, Nihon University, 1-8-14 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308, Japan
⁶ Department of Applied Physics, University of Miyazaki, 1-1 Gakuen Kibanadai-nishi, Miyazaki, Miyazaki 889-2192, Japan

Abstract

Monitor of All-sky X-ray Image (MAXI) on board International Space Station is capable of observing gamma-ray bursts (GRBs) and sending notices of GRBs or other transient events, using real time connection to the ground. MAXI observed 32 GRBs or short X-ray transients as of the end of September 2012. Among them, eleven events were simultaneously detected by other satellites. The observed rate of the MAXI GRBs is about one event per month. This rate is comparable to a past observation with larger effective area and larger field of view. The fact indicates that MAXI has better sensitivity to observe GRBs because of low background. The distribution of the spectral hardness of MAXI GRBs is similar to the results of a past instrument, which is sensitive to similar energy range.