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GCN Circular 33157

Subject
GRB 230111A: MAXI/GSC detection
Date
2023-01-12T00:28:35Z (a year ago)
From
Motoko Serino at Aoyama Gakuin U. <serino@phys.aoyama.ac.jp>
K. Setoguchi(Kyoto U.), T. Mihara (RIKEN), M. Serino (AGU),
H. Negoro, M. Nakajima, K. Kobayashi, M. Tanaka, Y. Soejima (Nihon U.),
T. Kawamuro, S. Yamada, T. Tamagawa, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU),
Y. Tsuboi, J. Kohara, S. Urabe, S. Nawa, N. Nemoto (Chuo U.),
M. Shidatsu, M. Iwasaki (Ehime U.),
N. Kawai, M. Niwano, R. Hosokawa, Y. Imai, N. Ito, Y. Takamatsu (Tokyo Tech),
S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, T. Kurihara (JAXA),
Y. Ueda, S. Ogawa, T. Yoshitake, K. Inaba, Y. Nakatani (Kyoto U.),
M. Yamauchi, T. Sato, R. Hatsuda, R. Fukuoka, Y. Hagiwara, Y. Umeki (Miyazaki U.),
K. Yamaoka (Nagoya U.),
Y. Kawakubo (LSU),
M. Sugizaki (NAOC) ,
W. Iwakiri (Chiba U.)

report on behalf of the MAXI team:
The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 19:07:37 UT on 11 Jan 2023.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (320.188 deg, -30.577 deg) = (21 20 45, -30 34 36) (J2000)
with a 90% C.L. statistical error of 0.22 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius).
Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners.
(319.214, -30.721) deg = (21 16 51, -30 43 15) (J2000)
(319.406, -31.127) deg = (21 17 37, -31 07 37) (J2000)
(321.653, -30.323) deg = (21 26 36, -30 19 22) (J2000)
(321.454, -29.920) deg = (21 25 48, -29 55 12) (J2000)
The X-ray flux averaged over the scan was 230 +- 30 mCrab
(4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at 17:34 UT
and in the next transit at 20:40 UT with an upper limit of 20 mCrab for each.
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