[vsnet-grb-info 25635] GRB 200514A: MAXI/GSC detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27735
SUBJECT: GRB 200514A: MAXI/GSC detection
DATE:    20/05/14 04:28:48 GMT
FROM:    Hitoshi Negoro at Nihon U  <negoro.hitoshi at nihon-u.ac.jp>

Y. Okamoto (Chuo U.), M. Nakajima, K. Kobayashi, H. Negoro,  
M. Aoki,  R. Takagi, K, Asakura, K, Seino, S. Mokumoto (Nihon U.), 
T. Mihara, C. Guo, Y. Zhou, T. Tamagawa, M. Matsuoka (RIKEN), 
T. Sakamoto, M. Serino, S. Sugita, H. Nishida, A. Yoshida (AGU), 
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, S. Kitakoga (Chuo U.), 
M. Shidatsu (Ehime U.), N. Kawai, R. Adachi, M. Niwano (Tokyo Tech), 
S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA), 
Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (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 on a bright uncatalogued X-ray transient source
at 02:21:15 UT on 2020 May 14.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (170.101 deg, 19.633 deg) = (11 20 24, +19 37 58) (J2000) 
with a statistical 90% C.L. elliptical error region 
with long and short radii of 0.26 deg and 0.21 deg, respectively. 
The roll angle of the long axis from the north direction is 46.0 deg counterclockwise. 
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 209 +- 38 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) = (169.291, 18.660) deg = (11 17 09, +18 39 36) (J2000)
(R.A., Dec) = (169.683, 18.463) deg = (11 18 43, +18 27 46) (J2000)
(R.A., Dec) = (170.979, 20.746) deg = (11 23 54, +20 44 45) (J2000)
(R.A., Dec) = (170.584, 20.945) deg = (11 22 20, +20 56 42) (J2000)
There was no significant excess flux in the previous transit at UT 00:45 UT
and in the next transit at 03:54 UT with an upper limit of 20 mCrab for each.

Swift/XRT followup observations are requested.