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MAXI/GSC detection of a brightening of X-ray binary pulsar 4U 0115+63

ATel #3430; T. Yamamoto (RIKEN), M. Nakajima (Nihon U), T. Mihara, M. Sugizaki, M. Serino, S. Nakahira, T. Sootome, M. Matsuoka (RIKEN), S. Ueno, H. Tomida, M. Kohama, M. Ishikawa (JAXA), N. Kawai, M. Morii, K. Sugimori, R. Usui, T. Toizumi (Tokyo Tech), A. Yoshida, K. Yamaoka (AGU), H. Tsunemi, M. Kimura, H. Kitayama (Osaka U.), H. Negoro, F. Suwa (Nihon U.), Y. Ueda, K. Hiroi, M. Shidatsu (Kyoto U.), Y. Tsuboi, T. Matsumura, K. Yamazaki (Chuo U.) report on behalf of the MAXI team
on 14 Jun 2011; 06:04 UT
Credential Certification: Tatehiro Mihara (mihara@crab.riken.jp)

Subjects: X-ray, Binary, Neutron Star, Pulsar

Referred to by ATel #: 3434, 3677, 8179, 10608

MAXI/GSC detection of a brightening of X-ray binary pulsar 4U 0115+63 MAXI/GSC detected an increase of X-ray flux from the X-ray binary pulsar 4U 0115+63. The daily-average flux in 4-10 keV reached 38+-6 mCrab on 2011 June 10. The orbital phase is 0.97 based on the ephemeris by Bildsten et al. (1997), suggesting that the current brightening was associated with the periastron passage of the pulsar. MAXI/GSC also detected the previous periastron peak on May 18. The peak flux on June 10 is about 1.5 times larger than that on May 18.

The MAXI/GSC flux once dropped to 20 mCrab on June 11, and is increasing again. The current (June 14) flux is 60 mCrab.

The last small outburst was detected by Fermi GBM (ATel #3408) peaking on May 22-23 (orbital phase ~ 0.21). Considering the orbital period of 24.3170 days, the peak of the current outburst is expected to occur on June 15-16, 2011.

http://maxi.riken.jp/top/index.php?cid=1&jname=J0118+637