MAXI/GSC detection of a new short X-ray transient MAXI J0636+146

ATel #9707; H. Negoro (Nihon U.), Y. Ono (Tokyo Tech), M. Serino (RIKEN), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara (JAXA), Y. E. Nakagawa (JAMSTEC), T. Mihara, M. Sugizaki, W. Iwakiri, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N. Kawai, N. Isobe, S. Sugita, T. Yoshii, Y. Tachibana, T. Fujiwara, S. Harita, Y. Muraki (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU), H. Tsunemi, R. Shomura (Osaka U.), M. Nakajima, K. Tanaka, T. Masumitsu, T. Kawase (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto (Kyoto U.), Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.), M. Yamauchi, K. Furuya (Miyazaki U.), K. Yamaoka (Nagoya U.)
on 4 Nov 2016; 04:43 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 short X-ray transient at 02:20 (UT) on 2016 November 4 in the 4 orbit (~6 hours) time bin (Negoro et al. 2016, PASJ, 68, S1). The source was visible on X-ray images of scan transients at 23:15 on November 03, and 00:47 on November 04.

Assuming that the source flux was constant over the above two transits, we obtain the source position at
(R.A., Dec) = (99.225 deg, 14.602 deg) = (06 36 53, +14 36 07) (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 long axis from the north direction is 72.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scans was 51 +- 13 mCrab (4.0-10.0keV, 1 sigma error). The source flux was not visible (< 30 mCrab) in the following scan transit at 02:20.

There is no bright catalogued source around the source position. Then, we tentatively name the source MAXI J0636+146. We encourage followup observations of this new X-ray transient.