TITLE: GCN CIRCULAR NUMBER: 25612 SUBJECT: LIGO/Virgo S190901ap: Coverage and upper limits from MAXI/GSC observations DATE: 19/09/02 07:32:02 GMT FROM: Motoko Serino at RIKEN/MAXI M. Serino, S. Sugita (AGU), H. Negoro (Nihon U.), 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 S190901ap at 2019-09-01 23:31:01.837 UTC (GCN #25606). At the trigger time of S190901ap, the high-voltage of MAXI/GSC was on. The instantaneous field of view of GSC at the GW trigger time covered 1% of the 90% credible region of the bayestar sky map, in which we found no significant new X-ray source. The 4-orbit (360 min) observation with GSC after the event covered 72% of the 90% credible region of the bayestar skymap from 23:31:01 to 05:30:56 UTC (T0+0 to T0+21595 sec). No significant new source was found in the region in the 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.