[vsnet-grb-info 27181] GRB 210110A: MAXI/GSC detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29284
SUBJECT: GRB 210110A: MAXI/GSC detection
DATE:    21/01/10 17:00:16 GMT
FROM:    Motoko Serino at RIKEN/MAXI  <motoko at crab.riken.jp>

S. Yamada (Kyoto U.), H. Negoro (Nihon U.), M. Serino (AGU),
M. Nakajima, M. Aoki, K. Kobayashi, R. Takagi, K, Asakura, K, Seino (Nihon U.),
T. Mihara, 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, R. Hosokawa (Tokyo Tech),
S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA),
Y. Ueda, 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.), 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 15:14:40 on 2021 January 10.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (172.727 deg, -41.315 deg) = (11 30 54, -41 18 52) (J2000)
with a 90% C.L. statistical error of 0.30 deg and an additional 
systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 127 +- 25 mCrab
(4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at 13:41 UT
and in the next transit at 16:47 with an upper limit of 20 mCrab for each.