MAXI/GSC detection of a probable new X-ray transient MAXI J1820+070
ATel #11399; T. Kawamuro (NAOJ), H. Negoro (Nihon U.), T. Yoneyama (Osaka U.), S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai (JAXA), T. Mihara, M. Sugizaki, S. Nakahira, W. Iwakiri, F. Yatabe, Y. Takao, M. Matsuoka (RIKEN), N. Kawai, S. Sugita, T. Yoshii, Y. Tachibana, S. Harita, K. Morita (Tokyo Tech), A. Yoshida, T. Sakamoto, M. Serino, Y. Kawakubo, Y. Kitaoka, T. Hashimoto (AGU), H. Tsunemi (Osaka U.), M. Nakajima, T. Kawase, A. Sakamaki, W. Maruyama (Nihon U.), Y. Ueda, T. Hori, A. Tanimoto, S. Oda, T. Morita, S. Yamada (Kyoto U.), Y. Tsuboi, Y. Nakamura, R. Sasaki, H. Kawai, T. Sato (Chuo U.), M. Yamauchi, C. Hanyu, K. Hidaka (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Shidatsu (Ehime U.) report on behalf of the MAXI team
on 11 Mar 2018; 16:41 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Hitoshi Negoro (negoro@phys.cst.nihon-u.ac.jp)
Subjects: X-ray, Black Hole, Neutron Star, Transient
Referred to by ATel #: 11400, 11403, 11418, 11421, 11423, 11424, 11425, 11426, 11427, 11432, 11437, 11439, 11440, 11445, 11451, 11458, 11480, 11488, 11490, 11510, 11533, 11539, 11540, 11574, 11576, 11578, 11609, 11723, 11820, 11831, 11833, 11887, 11899, 12057, 12061, 12064, 12128, 12157, 12534, 12596, 12608, 12688, 12988, 13066, 13502, 13530, 14492, 16192
The MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray transient source at 12:50 UT on 2018 March 11. Using GSC camera GSC_2 and GSC_7 data of 5 scan transits from 2018-03-11 19:48 to 2018-03-12 02:04, we obtain the source position at
(R.A., Dec) = (275.112 deg, 7.037 deg) = (18 20 26, +07 02 13) (J2000)
with a statistical 90% C.L. elliptical error region with long and short radii of 0.47 deg and 0.38 deg, respectively. The roll angle of the long axis from the north direction is 28.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 32 +- 9 mCrab (4.0-10.0keV, 1 sigma error).
Since there is no known X-ray source in the error region, we tentatively name the source MAXI J1820+070.
Follow-up observations are encouraged.
MAXI J1820+070 information
