[vsnet-grb-info 14283] GRB 131215A: MAXI/GSC detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15597
SUBJECT: GRB 131215A: MAXI/GSC detection
DATE:    13/12/15 12:10:27 GMT
FROM:    H. Negoro at Nihon U.  <negoro at phys.cst.nihon-u.ac.jp>

K. Fukushima, H. Negoro (Nihon U.),
S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Morii, M. Serino,  J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN),
N. Kawai, R. Usui, T. Yoshii, Y. Tachibana (Tokyo Tech), 
A. Yoshida, T. Sakamoto, Y. Nakano, Y. Kawakubo, H. Ohtsuki (AGU), 
H. Tsunemi, M. Sasaki (Osaka U.), 
M. Nakajima, H. Sakakibara, T. Onodera, K. Suzuki (Nihon U.), 
Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.), 
Y. Tsuboi, M. Higa (Chuo U.), 
M. Yamauchi, K. Yoshidome, Y. Ogawa, H. Yamada (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
UT 2013-12-15T09:08:20.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (258.654 deg, 7.862 deg) = (17 14 36, +07 51 43) (J2000) 
with a statistical 90% C.L. elliptical error region 
with long and short radii of 0.25 deg and 0.21 deg, respectively. 
The roll angle of the long axis from the north direction is 90.0 deg counterclockwise. 
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 350 +- 55 mCrab (4-10keV, 1 sigma error).
Without the assumption about the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(R.A., Dec) = (258.538 deg, 7.338 deg) = (17 14 09, +07 20 16) (J2000)
(R.A., Dec) = (258.123 deg, 7.633 deg) = (17 12 29, +07 37 59) (J2000)
(R.A., Dec) = (258.913 deg, 8.557 deg) = (17 15 39, +08 33 24) (J2000)
(R.A., Dec) = (259.333 deg, 8.266 deg) = (17 17 19, +08 15 57) (J2000)

There was no significant excess flux in the previous transit at 07:35 UT
and in the next transit at 10:50 UT with an upper limit of 20 mCrab for each.