MAXI/GSC detection of a new X-ray outburst from the LMXB 4U 1608-52

ATel #6550; H. Negoro (Nihon U.), M. Serino (RIKEN), S. Ueno, H. Tomida, S. Nakahira, 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, T. Yoshii, Y. Tachibana (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, D. Uchida (Osaka U.), M. Nakajima, K. Fukushima, T. Onodera, K. Suzuki, T. Namba, M. Fujita, F. Honda (Nihon U.), Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.), Y. Tsuboi, A. Kawagoe (Chuo U.), M. Yamauchi, Y. Morooka, D. Itoh (Miyazaki U.), K. Yamaoka (Nagoya U.)
on 7 Oct 2014; 16:33 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 detected renewed X-ray activity from the low mass X-ray binary 4U 1608-52 (X 1608-522) at UT 13:00 on 2014 October 5 (MJD 56935). The 4-10 keV X-ray fluxes obtained with MAXI/GSC were 34 +- 18 mCrab averaged over 2 scan transits from 16:53 to 18:26 on Oct. 4, 107 +- 16 mCrab over 4 scans from 13:00 to 17:38 on Oct. 5, and 298 +- 29 mCrab over 3 scans from 12:12 to 15:17 on Oct. 6.
Since the 15-50 keV X-ray flux obtained with Swift/BAT on Oct. 6 was still below the detection (http://http://swift.gsfc.nasa.gov/results/transients/H1608-522/), the source was in a soft state.

This is the 6th outburst from the source since the long outburst in 2007-2009 (Linares et al. ATel #2264). The previous outbursts were starting on 2010 March 2 (ATel #2462), 2011 March 24 (ATel #3237), 2012 October 10 (ATel #4478), 2013 May 27 (ATel #5094) and 2014 January 16 (ATel #5990).

MAXI 4U 1608-52