TITLE: GCN CIRCULAR NUMBER: 27750 SUBJECT: GRB 200517A: MAXI/GSC detection DATE: 20/05/17 12:46:55 GMT FROM: Motoko Serino at RIKEN/MAXI M. Niwano (Tokyo Tech), H. Negoro (Nihon U.), M. Serino (AGU), M. Nakajima, M. Aoki, K. Kobayashi, R. Takagi, K, Asakura, K, Seino, S. Mokumoto (Nihon U.), T. Mihara, C. Guo, Y. Zhou, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.), M. Shidatsu (Ehime U.), N. Kawai, R. Adachi (Tokyo Tech), S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA), Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (Kyoto U.), H. Tsunemi (Osaka U.), M. Yamauchi, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC) report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 11:27:21 UT . We obtained the source position at (R.A., Dec) = (17.230 deg, -50.745 deg) = (01 08 55, -50 44 41) (J2000) with a rectangular error box with the following corners: (15.411, -49.816) deg = (01 01 38, -49 48 57) (J2000) (15.002, -50.346) deg = (01 00 00, -50 20 45) (J2000) (18.572, -51.401) deg = (01 14 17, -51 24 03) (J2000) (18.949, -50.859) deg = (01 15 47, -50 51 32) (J2000) There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 198 +- 33 mCrab (4.0-10.0keV, 1 sigma error). There was no significant excess flux in the previous transit at 09:54 UT with an upper limit of 20 mCrab.