MAXI/GSC discovery of a new hard X-ray transient MAXI J1847-004

ATel #13189; H. Negoro (Nihon U.), T. Yoneyama (Osaka U.), M. Serino (AGU), M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), 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. 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, 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), M. Sugizaki (NAOC)
on 14 Oct 2019; 01:41 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Hitoshi Negoro (negoro@phys.cst.nihon-u.ac.jp)

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The MAXI/GSC nova alert system triggered on a bright uncatalogued hard X-ray transient source at 15:33 UT on 2019 October 11. Assuming that the source flux was constant over 20 scan transits from 03:56 on October 12 to 17:06 on October 13, we obtain the source position at

(R.A., Dec) = (281.758 deg, -0.439 deg) = (18 47 01, -00 26 20) (J2000)

with a statistical 90% C.L. elliptical error region with long and short radii of 0.27 deg and 0.22 deg, respectively. The roll angle of the long axis from the north direction is 146.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The 4-10 keV flux changed from ~20 mCrab to ~190 mCrab in the above period.

Since there is no known bright X-ray source in the error region, we tentatively name the source MAXI J1847-004.
Followup observations are highly encouraged.

MAXI alert information