TITLE: GCN CIRCULAR NUMBER: 11980 SUBJECT: GRB 110426A: MAXI/GSC detection of a GRB DATE: 11/04/27 00:33:16 GMT FROM: Motoko Suzuki at RIKEN S. Nakahira (RIKEN), H. Negoro (Nihon U.), M. Matsuoka , T. Mihara, M. Sugizaki, M. Serino, T. Yamamoto, T. Sootome (RIKEN), S. Ueno, H. Tomida, M. Kohama, M. Ishikawa (JAXA), N. Kawai, M. Morii, K. Sugimori, R. Usui, T. Toizumi (Tokyo Tech), A. Yoshida, K. Yamaoka (AGU), H. Tsunemi, M. Kimura, H. Kitayama (Osaka U.), M. Nakajima, F. Suwa (Nihon U.), Y. Ueda, K. Hiroi, M. Shidatsu (Kyoto U.), Y. Tsuboi, T. Matsumura, K. Yamazaki (Chuo U.) report on behalf of the MAXI team: At the scan transit centered at UT 2011-04-26T15:08:36, MAXI/GSC detected a short X-ray transient lasting about 18 seconds within the 46 seconds triangular transit response of MAXI/GSC. Judging from its location and spectral hardness ratio, this transient is probably a gamma-ray burst. Since the emission was detected only for a fraction of the triangular transit response, the uncertainty of its position along the scan direction is large. Without assuming the source constancy, we obtain a rectangular error box (90%C.L.) with the following corners: (R.A., Dec) = (+219.64 deg,-9.51 deg) = (14 38 34, -09 30 36)(J2000) (R.A., Dec) = (+222.36 deg,-12.97 deg) = (14 49 26, -12 58 12)(J2000) (R.A., Dec) = (+222.57 deg,-12.77 deg) = (14 50 17, -12 46 12)(J2000) (R.A., Dec) = (+219.84 deg,-9.31 deg) = (14 39 21, -09 18 36)(J2000) There is additional systematic uncertainty of 0.2 deg (90% containment radius). The preliminary flux (2-20 keV) of the source was at least 200 mCrab. There was no significant detection at the transit location in the previous and following orbits (92 min before or after the detection) with an upper limit of 20 mCrab. There is no known bright X-ray source at the detected position. Follow-up observations are encouraged.