TITLE: GCN CIRCULAR NUMBER: 25511 SUBJECT: LIGO/Virgo S190828l: Coverage and upper limits from MAXI/GSC observations DATE: 19/08/28 10:16:23 GMT FROM: Hitoshi Negoro at Nihon U H. Negoro (Nihon U.), M. Serino, S. Sugita (AGU), N. Kawai, M. Sugizaki (Tokyo Tech), M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.), M. Shidatsu (Ehime U.), M. Oeda, K. Shiraishi (Tokyo Tech), S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, N. Isobe, R. Shimomukai, M. Tominaga (JAXA), Y. Ueda, A. Tanimoto, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (Kyoto U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, S. Iwahori, Y. Kurihara, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU) report on behalf of the MAXI team: We examined MAXI/GSC all-sky X-ray images (2-20 keV) after the LVC trigger S190828l at 2019-08-28 06:55:09.886 UTC (GCN 25503). At the trigger time of S190828l, the high-voltage of MAXI/GSC was off, and it was turned on at T0+387 sec (+6.5 min). The first one-orbit (92 min) scan observation with GSC after the event covered 94% of the 90% credible region of the bayestar skymap from 07:01:46 to 08:10:26 UTC (T0+397 to T0+4517 sec). No significant new source was found in the region in the one-orbit scan observation. A typical 1-sigma averaged upper limit obtained in one scan observation is 20 mCrab at 2-20 keV. If you require information about X-ray flux by MAXI/GSC at specific coordinates, please contact the submitter of this circular by email.