GCN Circular 24049

S. Yamada (Kyoto U.), H. Negoro, M. Nakajima (Nihon U.), W. Iwakiri (Chuo, U.), 
W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), T. Mihara, S. Nakahira, 
M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, T. Hashimoto, A. Yoshida (AGU), 
Y. Tsuboi,  R. Sasaki, H. Kawai, T. Sato (Chuo U.), N. Kawai, M. Sugizaki, 
Y. Tachibana, K. Morita, 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, T. Morita, S. Ogawa (Kyoto U.), H. Tsunemi, 
T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, S. Iwahori, 
Y. Kurihara (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), 
M. Shidatsu (Ehime U.), Y. Kawakubo (LSU)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray transient 
source at 13:14:08 UT on 2019 April 04.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (220.987 deg, -22.632 deg) = (14 43 56, -22 37 55) (J2000) 
with a statistical 90% C.L. elliptical error region 
with long and short radii of 0.13 deg and 0.11 deg, respectively. 
The roll angle of the long axis from the north direction is 67.0 deg counterclockwise. 
Without assumptions on the source constancy, we obtain a rectangular error box
for the transient source with the following corners: 
(221.159, -22.965) deg = (14 44 38, -22 57 53) (J2000) 
(221.325, -22.771) deg = (14 45 17, -22 46 15) (J2000) 
(220.273, -22.002) deg = (14 41 05, -22 00 07) (J2000) 
(220.107, -22.196) deg = (14 40 25, -22 11 45) (J2000) 
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 378 +- 40 mCrab (4.0-10.0keV, 1 sigma error).

There was no significant excess flux in the previous transit at 11:41 UT with an upper limit of 20 mCrab.
Note that we rename GRB 190404B in the MAXI new-transient ML GRB 190404C.