[vsnet-grb-info 10941] MAXI/GSC detection of a short soft X-ray transient

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12360
SUBJECT: MAXI/GSC detection of a short soft X-ray transient
DATE:    11/09/20 09:39:23 GMT
FROM:    Motoko Suzuki at RIKEN  <motoko at crab.riken.jp>

M. Kohama(JAXA), T. Toizumi(Tokyo Tech), H. Negoro (Nihon U.),
M. Serino(RIKEN), S. Ueno, H. Tomida, M. Ishikawa (JAXA),
M. Matsuoka ,T. Mihara, M. Sugizaki, S. Nakahira, 
T. Yamamoto, T. Sootome (RIKEN), 
N. Kawai, M. Morii, K. Sugimori, R. Usui (Tokyo Tech),
A. Yoshida, K. Yamaoka (AGU),
H. Tsunemi, M. Kimura, H. Kitayama (Osaka U.), 
M. Nakajima, F. Suwa (Nihon U.), 
Y. Ueda, K. Hiroi, M. Shidatsu (Kyoto U.),
Y. Tsuboi, T. Matsumura, K. Yamazaki (Chuo U.)
report on behalf of the MAXI team:

MAXI/GSC triggered at UT 2011-09-16T20:33:01 on a bright uncatalogued 
soft X-ray transient source. 
The best-fit position of the source is

 (R.A., Dec) = (+171.57 deg, -17.71 deg) = (11 26 16, -17 42 22)(J2000)

Since the emission was detected only for a fraction of the triangular 
transit response, the uncertainty of its position along the scan direction 
is large.  Without assuming the source constancy, we obtain a rectangular 
error box (90%C.L.) with the following corners: 

 (R.A., Dec) = (+170.94 deg, -17.43 deg) = (11 23 45, -17 25 47)(J2000)
 (R.A., Dec) = (+171.14 deg, -17.18 deg) = (11 24 34, -17 10 35)(J2000)
 (R.A., Dec) = (+172.19 deg, -18.00 deg) = (11 28 46, -17 59 51)(J2000)
 (R.A., Dec) = (+171.98 deg, -18.24 deg) = (11 27 55, -18 14 37)(J2000)

The preliminary flux (4-10 keV) of the source is approximately 150 mCrab.
There was no significant detection at this position
in the previous and the following transits (92 min before and after the detection)
with an upper limit of 20 mCrab.
There is no known bright source at the detected position.