[vsnet-grb-info 15397] GRB 140814A: MAXI/GSC detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16686
SUBJECT: GRB 140814A: MAXI/GSC detection
DATE:    14/08/14 12:55:45 GMT
FROM:    H. Negoro at Nihon U.  <negoro at phys.cst.nihon-u.ac.jp>

D. Uchida (Oasaka U.), 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 (Osaka U.),
H. Negoro, 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, 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 2014-08-14T07:12:31 UT. 
Assuming that the source flux was constant over the transit,
we obtain the source position at

  (R.A., Dec) = (182.515 deg, 49.348 deg) = (12 10 03, +49 20 52) (J2000) 

with a statistical 90% C.L. elliptical error region with long and short radii 
of 0.33 deg and 0.27 deg respectively. 
The roll angle of long axis from the north direction is 126.0 deg 
counterclockwise. There is an additional systematic uncertainty of 0.1 deg 
(90% containment radius). The X-ray flux averaged over the scan was 
232 +- 45 mCrab (4-10keV, 1 sigma error).

 Without assumptions on the source constancy,we obtain a rectangular error
box for the transient source with the following corners:

(R.A., Dec) = (182.052 deg, 48.309 deg) = (12 08 12, +48 18 32) (J2000)
(R.A., Dec) = (181.153 deg, 48.617 deg) = (12 04 36, +48 37 00) (J2000)
(R.A., Dec) = (182.777 deg, 50.186 deg) = (12 11 06, +50 11 07) (J2000)
(R.A., Dec) = (183.701 deg, 49.873 deg) = (12 14 48, +49 52 21) (J2000)

 There was no significant excess flux in the previous transit at UT 5:39 and 
in the next transit at 8:43 UT with an upper limit of 20 mCrab for each.
A burst spectrum is relatively soft, and a blackbody fit to the energy 
spectrum gives a temperature of about 1 keV.
Thus, a possibility of an X-ray burst can not be excluded.