MAXI/GSC detection of an X-ray transient MAXI J1930+093
ATel #5943; H. Negoro (Nihon U.), M. Serino, (RIKEN), S. Nakahira (JAXA), S. Ueno, H. Tomida, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA), T. Mihara, M. Sugizaki, M. Morii, J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN), N. Kawai, R. Usui, T. Yoshii, Y. Tachibana (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Nakano, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, M. Sasaki (Osaka U.), M. Nakajima, H. Sakakibara, K. Fukushima, T. Onodera, K. Suzuki (Nihon U.), Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.), Y. Tsuboi, M. Higa (Chuo U.), M. Yamauchi, K. Yoshidome, Y. Ogawa, H. Yamada (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team
on 3 Mar 2014; 17:56 UT
Credential Certification: Hitoshi Negoro (negoro@phys.cst.nihon-u.ac.jp)
Subjects: X-ray, Black Hole, Blazar, Cataclysmic Variable, Neutron Star, Transient
The MAXI/GSC nova alert system triggered a faint X-ray transient at 05:31:55 on March 2, 2014. Assuming that the source flux was constant over the transits, we obtain the source position at
(R.A., Dec) = (292.685 deg, 9.314 deg) = (19 30 44, +09 18 50) (J2000)
with a statistical 90% C.L. elliptical error region with long and short radii of 0.28 deg and 0.22 deg respectively. The roll angle of long axis from the north direction is 45.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The 2-10 keV flux has increased since the end of February, and reached approximately 10 mCrab. We note that a slight enhancement, recognized almost at the same position in the 3 years and 4.1 years integrated GSC images, shows long-term X-ray variability with peak fluxes of less than about 5 mCrab. There are two RASS sources within the error region, 2FGL J1931.1+0938 (aka 1RXSJ193109.5+093714) and 1RXS J193121.5+092947. This enhancement is the brightest flare or outburst after the launch of MAXI even if it is due to one of these two sources. Since a possibility of a new transient can not be excluded, we tentatively name the source MAXI J1930+093. (Note that, as already reported in the MAXI transient alert email [New-transient:97], we refined the source position from that firstly reported in the alert email [New-transient:96]. Accordingly we also changed the tentative name from MAXI J1928+087.)
The followup observations are strongly encouraged to reveal the nature of the source.
