[vsnet-grb-info 16216] GRB 150222B: MAXI/GSC detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17497
SUBJECT: GRB 150222B: MAXI/GSC detection
DATE:    15/02/23 11:08:51 GMT
FROM:    H. Negoro at Nihon U.  <negoro at phys.cst.nihon-u.ac.jp>

T. Hori (Kyoto U.), H. Negoro (Nihon U.), M. Serino (RIKEN), 
S. Ueno, H. Tomida, S. Nakahira, 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, M. Fujita, F. Honda, T. Namba (Nihon U.),
Y. Ueda, M. Shidatsu, T. Kawamuro (Kyoto U.),
Y. Tsuboi, A. Kawagoe (Chuo U.), M. Yamauchi, Y. Morooka, 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 05:24:16 UT on February 22.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (155.897 deg, -41.170 deg) = (10 23 35, -41 10 13) (J2000)
with a 90% C.L. statistical error of 0.39 deg and an additional 
systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 123 +- 26 mCrab
(4-10keV, 1 sigma error).
There was no significant excess flux in the previous transit at 23:13 UT
on February 21 and in the next transit at 06:56 UT on February 22
with an upper limit of 20 mCrab for each.