GCN Circular 14130

M. Higa (Chuo U.), H. Negoro (Nihon U.), M. Serino (RIKEN), 
S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa (JAXA), 
T. Mihara, M. Sugizaki, K. Morihana, T. Yamamoto, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), 
N. Kawai, M. Morii, R. Usui, K. Ishikawa (Tokyo Tech), 
A. Yoshida, T. Sakamoto, Y. Nakano (AGU), 
H. Tsunemi, M. Sasaki (Osaka U.), M. Nakajima, M. Asada (Nihon U.), 
Y. Ueda, K. Hiroi, M. Shidatsu, R. Sato, T. Kawamuro (Kyoto U.), 
Y. Tsuboi (Chuo U.), 
M. Yamauchi, Y. Nishimura, T. Hanayama, K. Yoshidome, Y. Ogawa (Miyazaki U.), 
K. Yamaoka (ISAS) report on behalf of the MAXI team

At 2013-01-02T04:41:42 UT, the MAXI/GSC nova alert system triggered 
on a bright uncatalogued X-ray transient source.
The transient emission started at 04:41:42 and lasted at least 
45 seconds within the 74 second long triangular transit response 
of MAXI/GSC. We identify this event as GRB 130102B.

Assuming that the source flux was constant over the transit,
we obtain the source position at

 (R.A., Dec) = (309.58 deg, -72.38 deg ) = (20 38 20, -72 22 36)(J2000)

with a 90% C.L. statistical error of 0.2 deg and an additional systematic 
uncertainty of 0.2 deg (90% containment radius). The 4-10 keV flux was 
320 +- 40 mCrab.

There was no significant excess flux in the previous transit at 03:09UT 
and in the next transit at 06:15 UT$B!!(Bwith an upper limit of 20 mCrab for each.