TITLE: GCN CIRCULAR NUMBER: 24177 SUBJECT: LIGO/Virgo S190425z: MAXI/GSC Observations DATE: 19/04/25 12:50:24 GMT FROM: Mutsumi Sugizaki at Tokyo Tech./MAXI M. Sugizaki, N. Kawai (Tokyo Tech), H. Negoro (Nihon U.), M. Serino, S. Sugita (AGU), M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), S. Nakahira, 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. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai, M. Tominaga (JAXA), Y. Ueda, A. Tanimoto, T. Morita, S. Yamada, S. Ogawa (Kyoto U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, S. Iwahori, Y. Kurihara (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU) report on behalf of the MAXI team: We examined the MAXI/GSC all-sky X-ray images (2-20 keV) obtained in the orbit after the LVC trigger S190425z at 2019-04-25 08:18:05.017 UTC (GCN 24168). At the trigger time of S190425z, the high-voltage of MAXI/GSC was off, and it was turned on at T0+1054 sec (=T0+17.5 min). The one-orbit (92 min) scan of GSC covered > 90% of the 90% error region of the bayestar skymap from 08:35:39 to 09:50:05 UTC (T0+1054 to T0+5520 sec). No significant new source was found in the error region at the one-orbit scan. The 1-sigma averaged upper limit obtained from the scan was 20 mCrab at 4-10 keV. If you require information of X-ray flux by MAXI/GSC at specific coordinates, please contact the submitter of this circular by email.