{
  "bibcode": "2022GCN.32756....1K",
  "body": "K. Kobayashi, H. Negoro, M. Nakajima, M. Tanaka, Y. Soejima (Nihon U.), \nT. Mihara, T. Kawamuro, S. Yamada, T. Tamagawa, M. Matsuoka (RIKEN), \nT. Sakamoto, M. Serino, S. Sugita, H. Hiramatsu, A. Yoshida (AGU), \nY. Tsuboi, W. Iwakiri, J. Kohara (Chuo U.), M. Shidatsu, M. Iwasaki (Ehime U.),\nN. Kawai, M. Niwano, R. Hosokawa, Y. Imai, N. Ito, Y. Takamatsu (Tokyo Tech), \nS. Nakahira,  S. Ueno, H. Tomida, M. Ishikawa,  T. Kurihara (JAXA), \nY. Ueda, S. Ogawa, K. Setoguchi, T. Yoshitake, K. Inaba (Kyoto U.), \nM. Yamauchi, T. Sato, R. Hatsuda, R. Fukuoka, Y. Hagiwara, Y. Umeki (Miyazaki U.), \nK. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), and M. Sugizaki (NAOC) \n\nWe reported the MAXI/GSC detection of the bright X-ray emission \nfrom GRB 221009A/Swift J1913.1+1946 (GCN 32632/ATel #15650) \nat 13:58 (T0+2.5 ks, where T0 is the Fermi GBM trigger time, GCN 32642), \n15:31 (T0+8.0 ks), and 17:04 (T+13.6 ks) (ATel #15651).\n\nFitting GSC energy spectra at these scans with an absorbed power-law model \ngives a photon index of 1.93 +/- 0.09, 2.1 +/- 0.3, and 2.1 +/- 0.5, respectively. \nAll the errors quoted are at the 90% confidence level. Here we fixed \nthe column densities at 6.75e21 cm^-2 at z = 0.151 and 5.4e21 cm^-2 at z = 0 \nobtained with the Swift XRT (GCN 32651). Unabsorbed 2-10 keV fluxes are \n(6.1 +/- 0.3)e-8 erg cm^-2 s^-1, (1.1 +/- 0.1)e-8 erg cm^-2 s^-1, and \n(0.7 +/- 0.1)e-8 erg cm^-2 s^-1, respectively.\n\nWe also note that the source was not detected in the transit at 12:25 UT \non October 9 (T0-3.1 ks) with an upper limit of 20 mCrab.\n\nWe crosspost this report to the ATel and the GCN because we initially \nregarded this event as a galactic transient, and posted the preliminary results \nonly to the ATel.",
  "circularId": 32756,
  "createdOn": 1665757770000,
  "email": "negoro.hitoshi@nihon-u.ac.jp",
  "subject": "MAXI/GSC refined analysis of the bright X-ray afterglow of GRB 221009A/Swift J1913.1+1946",
  "submitter": "Hitoshi Negoro at Nihon U  <negoro.hitoshi@nihon-u.ac.jp>",
  "eventId": "GRB 221009A"
}