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GCN Circular 25271

Subject
GRB 190805B: MAXI/GSC detection
Date
2019-08-05T05:32:21Z (5 years ago)
From
Hitoshi Negoro at Nihon U <negoro@cygnus.phys.cst.nihon-u.ac.jp>
T. Sato (Chuo U.), H. Negoro, M. Nakajima, W. Maruyama, M. Aoki, 
K. Kobayashi (Nihon U.), T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN), 
T. Sakamoto, M. Serino, S. Sugita, H. Nishida, A. Yoshida (AGU), 
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai (Chuo U.),  M. Shidatsu (Ehime U.),
N. Kawai, M. Sugizaki, M. Oeda, K. Shiraishi (Tokyo Tech), S. Nakahira, Y. Sugawara, 
S. Ueno, H. Tomida, M. Ishikawa, N.Isobe, 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)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered on an uncatalogued X-ray transient source 
at 04:49:12 UT on 2019 August 05.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (211.853 deg, 19.766 deg) = (14 07 24, +19 45 57) (J2000) 
with a statistical 90% C.L. elliptical error region 
with long and short radii of 0.30 deg and 0.29 deg, respectively. 
The roll angle of the long axis from the north direction is 170.0 deg counterclockwise. 
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 109 +- 18 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) = (210.974, 20.151) deg = (14 03 53, +20 09 03) (J2000) 
(R.A., Dec) = (210.941, 19.551) deg = (14 03 45, +19 33 03) (J2000) 
(R.A., Dec) = (212.931, 19.442) deg = (14 11 43, +19 26 31) (J2000) 
(R.A., Dec) = (212.971, 20.042) deg = (14 11 53, +20 02 31) (J2000) 
There was no significant excess flux in the previous transit at 03:16 UT
with an upper limit of 20 mCrab.

This burst is likely the same one that Fermi detected about 3 min earlier
(Trigger number 586673165).
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