MAXI/GSC, SSC and Swift/XRT observations of an X-ray flare from Algol

ATel #4656; S. Nakahira (JAXA), Y. Ogawa (Miyazaki U.), M. Matsuoka (RIKEN), M. Higa , Y. Tsuboi (Chuo U.) M. Kimura, S. Ueno, H. Tomida, M. Ishikawa, K. Yamaoka (JAXA), N. Kawai, M. Mori , R. Usui, K. Ishikawa (Tokyo Tech), H. Negoro, M. Asada (Nihon U.), T. Mihara, M. Sugizaki, M. Serino, K. Morihana, T. Yamamoto, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), A. Yoshida, T. Sakamoto, Y. Nakano (AGU), H. Tsunemi, M. Sasaki (Osaka U.), M. Nakajima, (Nihon U.), Y. Ueda, K. Hiroi, M. Shidatsu, R. Sato, T. Kawamuro (Kyoto U.), M. Yamauchi, Y. Nishimura, T. Hanayama, K. Yoshidome (Miyazaki U.) on behalf of the MAXI team
on 19 Dec 2012; 14:22 UT
Credential Certification: Satoshi NAKAHIRA (nakahira@crab.riken.jp)

Tweet

MAXI/GSC and SSC detected an X-ray flare from Algol. (Previous MAXI detections of flares from Algol: ATel #3096, #3809) The X-ray flux increased slowly from MJD56278.0 (2012 Dec 17 UT), and reached a peak of 48 +/- 10 mCrab in the GSC band (2-20 keV) at MJD 56278.36. Then it decayed with an e-folding time of 0.32 +/- 0.1 d. We immediately requested a Swift ToO observation referring the MAXI/GSC detection. A 2ksec snapshot was taken at 16:16 UT on 2012 Dec 17 (MJD 56278.678) with the WT mode. The energy spectrum shows an apparent emission line at 6.7 keV. The source spectrum can be well fitted by an absorbed thermal bremsstrahlung model and a gaussian line (reduced chisquare=1.15 ), with a plasma temperature of 4.2 +/- 0.2 keV and a line energy of 6.70 +/- 0.05 keV. The spectrum can be also presented by MEKAL model (Mewe, R., et al. AAS. 62, 197?254) (reduced chisquare=1.05) with a plasma temperature kT= 4.35 +/- 0.16 keV and an abundance 0.32 +/- 0.05 of the solar value. The 2-10 keV X-ray flux of was 15 mCrab. We thank the Swift team for scheduling the ToO observation.