MAXI/GSC also detected the newly discovered X-ray transient source Swift J0549.7-6812

ATel #5289; K. Fukushima, H. Negoro (Nihon U), S. Nakahira (JAXA), T. Mihara, M. Sugizaki, M. Serino, M. Morii, T. Yamamoto, J. Sugimoto, T. Takagi, M. Matsuoka, (RIKEN), S. Ueno, H. Tomida, M. Kimura, M. Ishikawa, Y. Nakagawa (JAXA), N. Kawai, R. Usui, K. Ishikawa, T. Yoshii (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Nakano, Y. Kawakubo (AGU), H. Tsunemi, M. Sasaki (Osaka U.), M. Nakajima, T. Onodera, K. Suzuki (Nihon U.), Y. Ueda, M. Shidatsu, T. Kawamuro (Kyoto U.), Y. Tsuboi, M. Higa (Chuo U.), M. Yamauchi, K. Yoshidome, H. Yamada, Y. Ogawa (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team
on 16 Aug 2013; 05:39 UT
Credential Certification: Hitoshi Negoro (negoro@phys.cst.nihon-u.ac.jp)

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The MAXI transient alert system triggered on an unknown transient source in the direction of the Large Magellanic Cloud on August 6th, 2013 (MJD 56510.42). The triggered position (R.A., Dec) = (87.574, -68.309) with a typical error size of 0.3 deg is consistent with Swift J0549.7-6812 newly discovered with Swift/BAT (Krimm et al. ATel #5286).

The detection on August 6th was still at a low significance level (3.5 sigma level, about 7-8 mCrab). The preliminary analysis shows that the 4-10 keV count rate tends to have increased gradually since around July 27th, 2013, and reached 0.11 +- 0.02 counts/sec/cm2 (about 10 mCrab) on August 10th to 12th (MJD 56513-56515).

A similar flux level recently obtained with MAXI/GSC (4-10 keV) and Swift/BAT (15-50 keV) (ATel #5286) suggests that the source has a Crab-like spectrum. If the source locates in the LMC at the distance of 50 kpc, the source luminosity can be estimated to be approximately 7e37 erg/s, suggesting that the source is a black-hole candidate in the intermediate state or a LMXB neutron star in the hard state. The other possibility cannot be excluded.
Multiwavelength followup observations are strongly encouraged to reveal the nature of the source.