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MAXI detection of a super-burst from EXO 1745-248 in Terzan 5

ATel #3729; T. Mihara, M. Matsuoka, M. Sugizaki, M. Serino, S. Nakahira, T. Yamamoto, T. Sootome (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, M. Nakajima, 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 1 Nov 2011; 10:03 UT
Credential Certification: Tatehiro Mihara (mihara@crab.riken.jp)

Subjects: X-ray, Binary, Globular Cluster, Neutron Star, Transient

Referred to by ATel #: 3743

MAXI detected the initial burst component from EXO 1745-248 in Terzan 5 (ATel #3714, #3718, #3720). The light curve obtained by MAXI shows an exponential decay with an e-folding time of 10 hour. If the emission is originated by the blackbody radiation, the temperature can be estimated from the hardness of the two energy bands.

 
 MJD      4-10/2-4 keV    kT [keV]     10-20/4-10 keV   kT [keV] 
55858.53      2.9         2.9  ± 0.8     0.32     2.4  ± 0.6    
55858.59      1.5         1.7  ± 0.4     0.19     2.0  ± 0.8 
55858.78      1.05        1.4  ± 0.4     0.50     2.8  ± 1.0 
55858.84      1.24        1.58 ± 0.5     0.37     1.85 ± 0.8 
55858.91      1.06        1.43 ± 0.5     0.19     1.83 ± 1.5 
55858.97      1.03        1.40 ± 0.5     0.06     1.80 ± 3.9 
(Errors are 1-sigma.) 
The temperatures estimated from 4-10/2-4 keV and 10-20/4-10 keV are consistent with each other. It showed a softening from 2.9 keV in the beginning to 1.5 keV in the end. The fluence is 2.4 × 1042 erg in 2-10 keV assuming 8.7 kpc distance (Cohn et al. ApJ 571 818 (2002)). The sphere radius of the blackbody is 6.3 km with using 2 keV and 6.8 × 1037 erg/s at the peak. Those (e-folding time, temperature, softening, fluence, and radius) are typical as a super-burst from low-mass X-ray binaries. The light curve and temperature plot are available at http://maxi.riken.jp/top/index.php?cid=34 and http://maxi.riken.jp/top/index.php?cid=1&jname=J1748-248