New Outburst of the Ultraluminous Supersoft X-ray Source in M101
ATel #305; A. K.H. Kong (Harvard-Smithsonian Center for Astrophysics)
on 13 Jul 2004; 05:19 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Albert Kong (akong@cfa.harvard.edu)
Subjects: X-ray, Binary, Black Hole, Transient
Referred to by ATel #: 306, 311
A new outburst of the ultraluminous supersoft X-ray source in M101 (CXOU
J140332.3+542103) was detected during a recent 9.9 ks Chandra observation
on 2004 July 5. More than 200 counts was detected and the energy spectrum
can be fit with an absorbed blackbody model with kT=70+/-15 eV and
N_H=(2.2+/-1.7)e21 cm^-2 (90% uncertainties). The unabsorbed 0.3-7 keV
luminosity is 7.4e39 erg/s (d=6.7 Mpc) and the bolometric luminosity is
2e40 erg/s (derived from the normalization). The source entered the
low/hard state in 2004 January with 0.3-7 keV luminosity
of ~3e37 erg/s (ATEL #222); it was marginally
detected with 10 counts (0.1-7 keV) in the last Chandra
observation (42 ks) taken on 2004 May 9. The recent Chandra
observations indicate that the source is currently in transition,
possibly from the low/hard state to the high/supersoft state.
