TITLE:   GCN CIRCULAR
NUMBER:  16702
SUBJECT: GRB 140818A: MAXI/GSC detection
DATE:    14/08/18 06:29:01 GMT
FROM:    H. Negoro at Nihon U.  <negoro@phys.cst.nihon-u.ac.jp>

F. Honda, K. Suzuki, H. Negoro (Nihon U.), M. Serino (RIKEN), 
S. Nakahira, S. Ueno, H. Tomida, 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, T. Yoshii, Y. Tachibana (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, D. Uchida (Osaka U.),
Nakajima, K. Fukushima, T. Onodera, T. Namba, M. Fujita (Nihon U.), 
Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.), 
Y. Tsuboi, A. Kawagoe (Chuo U.), M. Yamauchi, 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 2014-08-18T08:31:56 UT. 
Assuming that the source flux was constant over the transit,
we obtain the source position at

 (R.A., Dec) = (199.554 deg, 6.888 deg) = (13 18 12, +06 53 15)  (J2000) 

with a statistical 90% C.L. statistical error of 0.07 deg and an additional systematic 
uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 1125 +- 62 mCrab mCrab (4-10keV, 1 sigma error).
A energy spectrum fit with the absorbed (Nh=2.5e20) power-law model gives 
a photon index of 1.03 (+0.13/-0.12).