MAXI/GSC observes Cyg X-3 in a soft-high state
ATel #2635; N. Kawai, M. Morii, K. Sugimori (Tokyo Tech), T. Mihara, Y. E. Nakagawa, M. Sugizaki, M. Suzuki, T. Yamamoto, T. Sootome, M. Matsuoka (RIKEN), K. Kawasaki, S. Ueno, H. Tomida, M. Kohama, M. Ishikawa (JAXA), A. Yoshida, K. Yamaoka, S. Nakahira (AGU), H. Tsunemi, M. Kimura (Osaka U.), H. Negoro, M. Nakajima H. Ozawa, F. Suwa (Nihon U.), Y. Ueda, N. Isobe, S. Eguchi, K. Hiroi (Kyoto U.), A. Daikyuji (Miyazaki U.), A. Uzawa, T. Matsumura, K. Yamazaki (Chuo U.) report on behalf of the MAXI team:
on 25 May 2010; 15:52 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Nobuyuki Kawai (nkawai@phys.titech.ac.jp)
Subjects: X-ray, Binary, Black Hole, Transient
MAXI/GSC has confirmed that Cyg X-3 is in its soft-high state.
The latest X-ray fluxes (daily average, Crab unit) in the three energy bands
are shown below. The fluxes in the low state are shown for comparison.
Date MJD 2-4 keV 4-10 keV 10-20 keV
------------------------------------------------------
May 22 55338 0.23 +-0.01 0.38 +-0.01 0.08 +-0.02
May 23 55339 0.24 +-0.01 0.40 +-0.01 0.01 +-0.03
------------------------------------------------------
Apr 14 55300 0.05 +-0.01 0.14 +-0.01 0.19 +-0.03 (low state)
------------------------------------------------------
The current soft X-ray flux is comparable to that in the previous high state
in 2009 September, and is about twice as high as the intermediate maxima in
2010 February reported in ATel #
2404. Cyg X-3 has not been observed with
MAXI/GSC in the last three weeks because it was either located in the sky
region covered by the detectors currently powered off due to HV breakdown
troubles, or, in the orbital pole. Cyg X-3 became temporarily visible to
MAXI due to the special attitude of the ISS for the shuttle docking. The
ISS is now back in the normal attitude, and Cyg X-3 is unobservable again
for the next several days until the unobservable region moves away from Cyg
X-3 by the precession of the ISS orbit.