MAXI/GSC detection of a hard X-ray transient MAXI J0206-749 near the SMC

ATel #13300; H. Negoro (Nihon U.), N. Kawai (Tokyo Tech), T. Mihara (RIKEN), M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi, R. Takagi (Nihon U.), C. Guo, Y. Zhou, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.), M. Shidatsu (Ehime U.), M. Oeda, K. Shiraishi (Tokyo Tech), S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, R. Shimomukai, M. Tominaga (JAXA), Y. Ueda, A. Tanimoto, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (Kyoto U.), H. Tsunemi, T. Yoneyama, 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) report on behalf of the MAXI team:
on 21 Nov 2019; 01:31 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 an uncatalogued X-ray transient source at 16:31 UT on November 20, 2019. Assuming that the source flux was constant over 13 scan transits from 21:58 on November 19 to 22:43 on November 20, we obtain the source position at

(R.A., Dec) = (31.664 deg, -74.930 deg) = (02 06 39, -74 55 49) (J2000)

with a 90% C.L. statistical error of 0.47 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 23 +- 4 mCrab (4.0-10.0keV, 1 sigma error).

The source flux has been increasing gradually for 10 days. On November 11, 2011, we discovered the white dwarf nova MAXI J0158-744 (Kimura et al. 2011, ATel #3756 , Morii et al. 2013, ApJ 779, 118; Li et al. 2012, ApJ 761, 99L) on the outskirt of the SMC. The position of MAXI J0206-749 lies 0.83 arc-deg from that of MAXI J0158-744, suggesting that MAXI J0206-749 is a member of the SMC. A hard source spectrum also suggests the source is an X-ray transient pulsar or a black hole binary in the hard state. There is no bright X-ray source in the error circle above, we tentatively name the source MAXI J0206-749.

Followup observations are strongly encouraged.

Trigger Information about MAXI J0206-749