TITLE: GCN CIRCULAR NUMBER: 20507 SUBJECT: LIGO/Virgo G268556/GW170104: MAXI/GSC observations DATE: 17/01/23 02:51:51 GMT FROM: Motoko Serino at RIKEN/MAXI M. Serino (RIKEN), N. Kawai, S.Sugita (Tokyo Tech), H. Negoro (Nihon U.), S. Ueno, H. Tomida, S. Nakahira, M. Ishikawa, Y. Sugawara (JAXA), Y. E. Nakagawa (JAMSTEC), T. Mihara, M. Sugizaki, W. Iwakiri, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N.Isobe, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara, S. Harita, Y. Muraki (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU), H. Tsunemi, R. Shomura (Osaka U.), M. Nakajima, K. Tanaka, T. Masumitsu, T. Kawase (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto, S. Oda (Kyoto U.), Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.), M. Yamauchi, K. Furuya (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team: We examined the MAXI/GSC all-sky X-ray images (2-20 keV) obtained in the orbit and the day after the LVC trigger G268556/GW170104 at 2017-01-04 10:11:58.599 UTC (GCN 20364). In the 92-min orbit, MAXI/GSC scanned more than 80% of the whole sky, which includes 89.3% of the 90% regions in the bayestar skymap. One day image covers 95.2% of the 90% regions in the bayestar skymap. No significant new source was found in these images. The upper limits for the X-ray flux are different depending on the part of the sky. For instance, typical 2-20 keV 1-sigma (3-sigma) upper limits obtained from the one-orbit and oneday images are 19 (56) mCrab and 5 (16) mCrab, respectively. MAXI/GSC also observed the position of GRB 170105A (GCN Circ. 20377, 20390, 20406). The first scan after the burst was at 2017-01-05T06:47 (UT). No significant emission was observed at the position at the scan. The 1-sigma (3-sigma) upper limits in 2-20 keV are 18 (54) mCrab.