TITLE: GCN CIRCULAR NUMBER: 15663 SUBJECT: GRB 140102A: MAXI/GSC detection DATE: 14/01/03 14:11:53 GMT FROM: Takanori Sakamoto at AGU M. Kimura (JAXA), T. Sakamoto (AGU), S. Nakahira (JAXA), S. Ueno, H. Tomida, M. Ishikawa, Y. E. Nakagawa (JAXA), T. Mihara, M. Sugizaki, M. Morii, M. Serino, J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN), N. Kawai, R. Usui, K. Ishikawa, T. Yoshii, Y. Tachibana (Tokyo Tech), A. Yoshida, Y. Nakano, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, M. Sasaki, D. Uchida (Osaka U.), H. Negoro, M. Nakajima, K. Fukushima, T. Onodera, K. Suzuki (Nihon U.), Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.), Y. Tsuboi, M. Higa (Chuo U.), M. Yamauchi, K. Yoshidome, Y. Ogawa, H. Yamada, Y. Morooka (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team: The MAXI/GSC Nova alert system triggered a bright uncatalogued X-ray transient source at 21:19:54 UT on 2014-01-02. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (211.813 deg, 1.477 deg) = (14 07 15, +01 28 37) (J2000) with a statistical 90% C.L. elliptical error region in long and short radii of 0.46 deg and 0.35 deg respectively. The roll angle of long axis from the north direction is 40.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). This uncatalogued X-ray source is temporary and positionally coincident with the Swift detected GRB 140102A (Hagen et al. GCN #15653). Using the data available from 21:16 to 21:23 UT, the MAXI/GSC spectrum is created from T0(BAT)+58.2 sec to T0(BAT)+219.2 sec (T0(BAT) is the trigger time of the Swift/BAT). An absorbed power-law model gives an acceptable fit to the data. The best fit photon index is 2.7 (-0.8/+1.0). The unabsorbed 2-20 keV flux is 2.3 (-0.8/+0.9) x 10^-9 erg/cm2/s. All the quoted errors are at the 90% confidence level. There was no significant excess flux in the previous transit at 19:47 UT and in the next transit at 22:53 UT with an upper limit of ~20 mCrab for each.