[vsnet-grb-info 16291] GRB 150313A: MAXI/GSC detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17572
SUBJECT: GRB 150313A: MAXI/GSC detection
DATE:    15/03/13 09:16:13 GMT
FROM:    Motoko Suzuki at RIKEN  <motoko at crab.riken.jp>

Y. Morooka (Miyazaki U.), M. Serino (RIKEN), H. Negoro (Nihon U.), S. Nakahira (JAXA),
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.),
M. Nakajima,  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, D. Itoh (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 03:52:04 UT.
Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(R.A., Dec) = (251.439 deg, -11.707 deg) = (16 45 45, -11 42 24) (J2000)
(R.A., Dec) = (251.141 deg, -11.484 deg) = (16 44 33, -11 29 03) (J2000)
(R.A., Dec) = (253.294 deg, -9.249 deg) = (16 53 10, -09 14 55) (J2000)
(R.A., Dec) = (253.579 deg, -9.484 deg) = (16 54 18, -09 29 03) (J2000)
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 226 +- 34 mCrab
(4-10keV, 1 sigma error).
Because the duration of this burst is short (about 5 s in 4-10 keV),
the flux above is underestimated and it might be as high as 7 Crab.
There was no significant excess flux in the previous transit at 02:19 UT
and in the next transit at 05:24 UT 
with an upper limit of 20 mCrab for each.