[vsnet-grb-info 22938] GRB 190708B: MAXI/GSC detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25037
SUBJECT: GRB 190708B: MAXI/GSC detection
DATE:    19/07/08 21:35:14 GMT
FROM:    Motoko Serino at RIKEN/MAXI  <motoko at crab.riken.jp>

Y. Kawakubo (LSU), M. Nakajima (Nihon U.), M. Serino (AGU),
H. Negoro, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.),
S. Nakahira, T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, H. Nishida, A. Yoshida (AGU),
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.),
M. Shidatsu (Ehime U.),
N. Kawai, M. Sugizaki, M. Oeda, K. Shiraishi (Tokyo Tech),
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, 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.)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 19:49:58 UT .
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (326.571 deg, 7.711 deg) = (21 46 17, +07 42 39) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.22 deg and 0.19 deg, respectively.
The roll angle of long axis from the north direction is 125.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 394 +- 60 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) = (325.953, 7.630) deg = (21 43 48, +07 37 47) (J2000)
(R.A., Dec) = (326.121, 7.246) deg = (21 44 29, +07 14 45) (J2000)
(R.A., Dec) = (327.396, 7.791) deg = (21 49 35, +07 47 27) (J2000)
(R.A., Dec) = (327.229, 8.175) deg = (21 48 54, +08 10 30) (J2000)
There was no significant excess flux in the previous transit at UT 19:29
and in the next transit at 21:02 UT with an upper limit of 20 mCrab for each.