[vsnet-grb-info 21707] GRB 190129A: MAXI/GSC detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23806
SUBJECT: GRB 190129A: MAXI/GSC detection
DATE:    19/01/29 13:21:11 GMT
FROM:    Satoshi Sugita at Aoyama Gakuin U.  <sugita at phys.aoyama.ac.jp>

S. Nakahira (RIKEN), S. Sugita (AGU),
H. Negoro, M. Nakajima, A. Sakamaki, W. Maruyama, M. Aoki, K.
Kobayashi (Nihon U.),
T. Mihara, F. Yatabe, Y. Takao, M. Matsuoka (RIKEN),
T. Sakamoto, M. Serino, Y. Kawakubo, T. Hashimoto, A. Yoshida (AGU),
N. Kawai, M. Sugizaki, Y. Tachibana, K. Morita (Tokyo Tech),
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai,
T. Midooka (JAXA),
Y. Ueda, A. Tanimoto, T. Morita, S. Yamada, S. Ogawa (Kyoto U.),
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.),
H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.),
M. Yamauchi, K. Hidaka, S. Iwahori (Miyazaki U.),
T. Kawamuro (NAOJ),
K. Yamaoka (Nagoya U.),
M. Shidatsu (Ehime U.),
Y. Kawakubo (LSU)
report on behalf of the MAXI team:
The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray
transient source at 12:21:40 UT on January 29, 2019.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (11.459 deg, -31.887 deg) = (00 45 50, -31 53 13) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.16 deg and 0.15 deg, respectively.
The roll angle of long axis from the north direction is 40.0 deg
counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90%
containment radius).
The X-ray flux averaged over the scan was 306 +- 37 mCrab
(4.0-10.0keV, 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) = (10.934, -32.736) deg = (00 43 44, -32 44 09) (J2000)
(R.A., Dec) = (11.230, -32.814) deg = (00 44 55, -32 48 50) (J2000)
(R.A., Dec) = (11.935, -30.870) deg = (00 47 44, -30 52 12) (J2000)
(R.A., Dec) = (11.645, -30.793) deg = (00 46 34, -30 47 34) (J2000)
There was no significant excess flux in the previous transit at UT 10:49
with an upper limit of 20 mCrab.