GRB 131215A

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.

S. Golenetskii, R.Aptekar, V. Pal'shin, D. Frederiks, P. Oleynik, M. 
Ulanov, D. Svinkin, A. Tsvetkova and T. Cline on behalf of the 
Konus-Wind team report:

The long GRB 131215A (MAXI/GSC detection and localization:
K. Fukushima et al., GCN 15597
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 ) was detected by Konus-Wind
in the waiting mode at about T0(MAXI)= 32900 s UT (09:08:20).

The burst began with a pulse with a duration of about 60 s, followed by 
a less intense emission lasting ~240 s. The total burst duration was 
about 300 s.

As observed by Konus-Wind, the burst had a fluence
of (1.4 +/- 0.3)x10^-5 erg/cm2 (in the 20 - 1200 keV energy range).

Modelling the K-W 3-channel time-integrated spectrum
(from T0(KW) to T0(KW)+300 s)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields
alpha = -1.28 (-0.27, +0.31), and
Ep = 263 (-87, +234) keV

All the quoted errors are estimated at the 1 sigma confidence level.

The K-W light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB131215A/