[vsnet-grb-info 22893] GRB 190706A: MAXI/GSC detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24992
SUBJECT: GRB 190706A: MAXI/GSC detection
DATE:    19/07/06 10:53:40 GMT
FROM:    Kazuki Shiraishi at Tokyo Institute of Technology  <shiraishi at hp.phys.titech.ac.jp>

K. Shiraishi (Tokyo Tech), H. Negoro, M. Nakajima, W. Maruyama, M. Aoki, K.
Kobayashi (Nihon U.),
S. Nakahira, 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, T. Sato (Chuo U.),
M. Shidatsu (Ehime U.),
N. Kawai, M. Sugizaki, M. Oeda (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.),
Y. Kawakubo (LSU)

report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered an uncatalogued X-ray transient
source at 03:26:23 UT on July 6, 2019.

Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (26.605 deg, -43.248 deg) = (01 46 25, -43 14 52) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.39 deg and 0.36 deg, respectively.
The roll angle of the long axis from the north direction is 51.0 deg
counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment
radius).
The X-ray flux averaged over the scan was 53 +- 16 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) = (26.800, -41.863) deg = (01 47 11, -41 51 46) (J2000)
(R.A., Dec) = (25.798, -41.961) deg = (01 43 11, -41 57 39) (J2000)
(R.A., Dec) = (26.264, -44.604) deg = (01 45 03, -44 36 14) (J2000)
(R.A., Dec) = (27.310, -44.502) deg = (01 49 14, -44 30 07) (J2000)

There was no significant excess flux in the previous transit at UT 01:53
and in the next transit at 04:59 UT with an upper limit of 20 mCrab for
each.