MAXI/GSC detection of the onset of the outburst from Be/X-ray binary pulsar A0535+26
ATel #7015; M. Nakajima (Nihon U.), T. Mihara (RIKEN), S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA), M. Sugizaki, M. Morii, M. Serino, 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.), H. Negoro, 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.) report on behalf of the MAXI team:
on 2 Feb 2015; 09:34 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Motoki Nakajima (nakajima.motoki@nihon-u.ac.jp)
Subjects: X-ray, Binary, Neutron Star, Transient, Pulsar
An onset of the X-ray outburst from the Be/X-ray binary pulsar A0535+26 was detected by the MAXI/GSC nova alert system on 2015 January 29 (MJD 57051). On the basis of the MAXI on-demand analysis, the current outburst started from MJD 57048. Using the orbital ephemeris (T_0=44943.5(MJD), Porb=111.0 d ; Giovannelli et al. 2013), the onset of the outburst is consistent with the 0.05 orbital phase. Comparing with the previous brightening (Atel#6569), the current outburst also started from the same orbital phase. The one-day averaged 4-10 keV flux increased from 10 +- 5 mCrab (MJD 57048) to 69 +- 7 mCrab (MJD 57052). The Swift/BAT hard X-ray transient monitor has also observed this brightening. On MJD 57051, the 15-50 keV flux has reached to 72 +- 10 mCrab. The timing of the current X-ray outburst episode matched nicely to the prediction based on the optical observation (Atel #6969), while the latest observed intensity exceeded the expected peak flux. We encourage the multi-wavelength observations. The latest light curve can be checked at the following pages;
MAXI(http://maxi.riken.jp/top/index.php?cid=1&jname=J0538+263),
Swift/BAT(http://swift.gsfc.nasa.gov/results/transients/1A0535p262/),
Fermi/GBM(http://gammaray.msfc.nasa.gov/gbm/science/pulsars/lightcurves/a0535.html),
and the BeXRB monitor page
(http://integral.esac.esa.int/bexrbmonitor/Plots/sim_plot_1A0535+262.html).