[vsnet-grb-info 21755] GRB 190204A: MAXI/GSC detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23854
SUBJECT: GRB 190204A: MAXI/GSC detection
DATE:    19/02/04 07:23:51 GMT
FROM:    Satoshi Nakahira at RIKEN  <nakahira at crab.riken.jp>

T. Oeda (Tokyo Tech), M. Nakajima (Nihon U.), S. Nakahira (RIKEN),
H. Negoro, A. Sakamaki, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), 
T. Mihara, F. Yatabe, Y. Takao, M. Matsuoka (RIKEN),
T. Sakamoto, M. Serino, S. Sugita, 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 X-ray transient at 05:45:55 UT on February 4, 2019.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (351.341 deg, 54.761 deg) = (23 25 21, +54 45 38) (J2000)
with a 90% C.L. statistical error of 0.10 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 2286 +- 126 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) = (350.693, 54.635) deg = (23 22 46, +54 38 05) (J2000)
(R.A., Dec) = (350.828, 54.512) deg = (23 23 18, +54 30 43) (J2000)
(R.A., Dec) = (352.146, 54.985) deg = (23 28 35, +54 59 05) (J2000)
(R.A., Dec) = (352.013, 55.110) deg = (23 28 03, +55 06 35) (J2000).

The trigger time and position was consistent with that of GRB 190204A detected 
by Swift (Lien et al. 2019, GCN 23852).