MAXI/GSC detection an onset of outburst from Be/X-ray binary pulsar, GRO J1008-57

ATel #5705; A. Kawagoe (Chuo U.), T. Mihara, M. Sugizaki (RIKEN), M. Nakajima (Nihon U.), S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA), M. Morii, M. Serino, 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.), H. Negoro, 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 28 Dec 2013; 03:18 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Motoki Nakajima (nakajima.motoki@nihon-u.ac.jp)

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At 2013-12-26 19:54:30(UT), the MAXI Nova alert system detected an X-ray flux increase from the position consistent with the Be/X-ray binary pulsar, GRO J1008-57. According to the binary orbital parameter refined by Kuehnel et al. 2013, the current orbital phase is ~ -0.04 in the 249.46 day period, just 10 days before the periastron. Therefore, the observed X-ray increase is considered to be an onset of a normal outburst emerged near the periastron passage. GRO J1008-57 exhibited an giant outburst in 2012 November (ATel #4561) and then a normal outburst in 2013 April (ATel#5004) in last two orbital cycles. The source seems to be still active.

The latest light curve and the image are available at the following
URL: http://maxi.riken.jp/top/index.php?cid=1&jname=J1009-582

The folded light curve by the orbital period obtained from the MAXI/GSC data is placed at
http://maxi.riken.jp/news/en