MAXI/GSC discovery of a new X-ray transient MAXI J1727-203
ATel #11683; T. Yoneyama (Osaka U.), H. Negoro, M. Nakajima, A. Sakamaki, W. Maruyama (Nihon U.), T. Mihara, S. Nakahira, F. Yatabe, Y. Takao, M. Matsuoka (RIKEN), N. Kawai, M. Sugizaki, Y. Tachibana, K. Morita (Tokyo Tech), T. Sakamoto, M. Serino, S. Sugita, Y. Kawakubo, T. Hashimoto, A. Yoshida (AGU), S. Ueno, H. Tomida, M. Ishikawa, N. Isobe, Y. Sugawara, R. Shimomukai (JAXA), Y. Ueda, A. Tanimoto, T. Morita, S. Yamada (Kyoto U.), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.), H. Tsunemi (Osaka U.), M. Yamauchi, K. Hidaka, S. Iwahori (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), M. Shidatsu (Ehime U.)
on 5 Jun 2018; 14:29 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, Star, Transient
The MAXI/GSC nova alert system (Negoro et al. 2016, PASJ, 68, S1) triggered on an uncatalogued X-ray transient source at 09:41 UT on 2018 June 05. Assuming that the source flux was constant over three scan transits from 9:41 to 12:46,
we obtain the source position at
(R.A., Dec) = (261.971 deg, -20.389 deg) = (17 27 53, -20 23 20) (J2000)
with a statistical 90% C.L. elliptical error region with long and short radii of 0.33 deg and 0.28 deg, respectively. The roll angle of the long axis from the north direction is 154.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scans was 37 +- 8 mCrab (4.0-10.0keV, 1 sigma error).
Since the source is in the direction of the Galactic bulge, (l, b) = (5.2, 8.1), there are several 1RXS X-ray sources in the error region, e.g., 1RXS J172854.8-202151 (0.24 deg apart), and 1RXS J172903.6-202208 (0.27 deg apart). We, however, tentatively name this new transient source MAXI J1727-203 because no X-ray nova activity was reported from the 1RXS sources.
Followup observations are strongly encouraged to reveal the nature of this new transient.
Alert Information on MAXI J1727-203
