GCN Circular 16864

M. Morii, M. Serino (RIKEN), M. Nakajima, H. Negoro (Nihon U.),
S. Nakahira, S. Ueno, H. Tomida, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, 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.),
K. Fukushima, T. Onodera, K. Suzuki, T. Namba, M. Fujita, F. Honda (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:

MAXI/GSC observed the field of GRB 140928A at a scan transit centered 
at 2014-09-28 10:41:09 UT with a triangular response of 123-s duration.
This center time is 675 sec after the Fermi/GBM trigger time (2014-09-28 10:29:53.55 UT, GCN  #16850).
The source was located on the edge of the FoV where the source PSF was only partially covered in the    sensitive region of the GSC.
We therefore estimated the flux using PSF fitting of the photon image.
We marginally detected the afterglow of this GRB with
29 +17/-14 mCrab (4-10 keV) and 13 +11/-8  mCrab (2-4 keV) (1 sigma errors).
Here, we assumed the source constancy during the scan transit.
We did not detect this source at the previous scan (centered at 09:08:25 UT)
and the following scan (centered at 12:13:46 UT), with upper limits of 14 mCrab and 35 mCrab (90% C.L., 4-10 keV),
respectively.