TITLE: GCN CIRCULAR NUMBER: 17246 SUBJECT: GRB 141229A: MAXI/GSC detection DATE: 14/12/29 13:14:51 GMT FROM: H. Negoro at Nihon U. M. Fujita, H. Negoro (Nihon U.), M. Serino (RIKEN), S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA), T. Mihara, M. Sugizaki, M. Morii, J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN), N. Kawai, Y. Tachibana, T. Yoshii (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, D. Uchida (Osaka U.), M. Nakajima, K. Fukushima, T. Onodera, K. Suzuki, F. Honda, T. Namba (Nihon U.), Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.), Y. Tsuboi, A. Kawagoe (Chuo U.), M. Yamauchi, Y. Morooka, D. Itoh (Miyazaki U.), K. Yamaoka (Nagoya U.) The MAXI/GSC nova-alert system triggered a bright uncatalogued X-ray transient source at UT 11:49:02 on 2014 December 29. We obtain a rectangular error box for the transient source with the following corners: (R.A., Dec) = (71.479 deg, -18.956 deg) = (04 45 54, -18 57 20) (J2000) (R.A., Dec) = (71.846 deg, -18.494 deg) = (04 47 22, -18 29 38) (J2000) (R.A., Dec) = (72.599 deg, -19.778 deg) = (04 50 23, -19 46 41) (J2000) (R.A., Dec) = (72.961 deg, -19.311 deg) = (04 51 50, -19 18 40) (J2000) There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 179 +- 29 mCrab (4-10keV, 1 sigma error). There was no significant excess flux in the previous transit at UT 10:16.