TITLE:   GCN CIRCULAR
NUMBER:  28726
SUBJECT: GRB 201021B MAXI/GSC detection
DATE:    20/10/21 18:31:15 GMT
FROM:    Satoshi Nakahira at RIKEN  <nakahira@crab.riken.jp>

S. Nakahira (JAXA), M. Serino (AGU), Y. Kawakubo (LSU),
H. Negoro, M. Nakajima, M. Aoki, K. Kobayashi, R. Takagi, K, Asakura, K, Seino (Nihon U.),��
T. Mihara, C. Guo, Y. Zhou, T. Tamagawa, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, H. Nishida, K. Komachi, A. Yoshida (AGU),��
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.),��
M. Shidatsu (Ehime U.),
N. Kawai, R. Adachi, M. Niwano (Tokyo Tech),��
Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA),��
Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake, U. Goto, R. Uematsu (Kyoto U.),��
H. Tsunemi (Osaka U.),��
M. Yamauchi, K. Kurogi, K. Miike (Miyazaki U.),��
T. Kawamuro (NAOJ),��
K. Yamaoka (Nagoya U.),
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 2020-10-21T16:18:55UT .
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (3.592 deg, -63.535 deg) = (00 14 22, -63 32 05) (J2000)
with a 90% C.L. statistical error of 0.24 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 212 +- 25 mCrab (4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at UT 14:46��
and in the next transit at 17:51 UT with an upper limit of 20 mCrab for each.