[vsnet-grb-info 24888] GRB 200205A: MAXI/GSC detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26987
SUBJECT: GRB 200205A: MAXI/GSC detection
DATE:    20/02/05 11:00:12 GMT
FROM:    Motoko Serino at RIKEN/MAXI  <motoko at crab.riken.jp>

M. Niwano (Tokyo Tech), T. Mihara (RIKEN), M. Nakajima (Nihon U.), M. Serino (AGU),
H. Negoro, W. Maruyama, M. Aoki, K. Kobayashi, R. Takagi (Nihon U.),
C. Guo, Y. Zhou, T. Tamagawa, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, H. Nishida, A. Yoshida (AGU),
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.),
M. Shidatsu (Ehime U.),
N. Kawai, M. Oeda, K. Shiraishi (Tokyo Tech),
S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, R. Shimomukai, M. Tominaga (JAXA),
Y. Ueda, A. Tanimoto, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (Kyoto U.),
H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.),
M. Yamauchi, S. Iwahori, Y. Kurihara, K. Kurogi, K. Miike (Miyazaki U.),
T. Kawamuro (NAOJ),
K. Yamaoka (Nagoya U.),
Y. Kawakubo (LSU),
M. Sugizaki (NAOC) 
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at UT 2020-02-05T06:54.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (130.230 deg, -35.413 deg) = (08 40 55, -35 24 46) (J2000)
with a 90% C.L. statistical error of 0.17 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius).
This position is consistent with that of GRB 200205A triggered by Swift (GCN#26982) on 2020-02-05T06:35.
The X-ray flux in 4.0-10.0 keV energy band rapidly incrased, 72 mCrab (2020-02-05T06:54) to 262 mCrab (2020-02-05T07:16).  
In the next transit at 2020-02-05T08:27, the source was detected only in the 2.0-4.0 keV energy band with the flux of 66 +- 18 mCrab. 
There was no significant excess flux in the previous transit at UT 05:43
and in the next transit at 08:49 UT with an upper limit of 20 mCrab for each.