Swift follow-up of X-ray transients in M31
ATel #899; W. Pietsch (MPE), F. Haberl (MPE), J. Greiner (MPE), H. Stiele (MPE)
on 27 Sep 2006; 16:44 UT
Credential Certification: Wolfgang Pietsch (wnp@mpe.mpg.de)
Subjects: X-ray, Binary, Black Hole, Neutron Star, Transient
Referred to by ATel #: 969
On 2006, September 11, a 4 ks SWIFT observation of the M31 center field
was performed to further monitor
the outbursts of the X-ray transients reported in ATel #881. The black
hole transient candidate SWIFT J004217.3+411532 dropped in source intensity by
20% compared to the SWIFT observation 10 days earlier. Its X-ray spectrum did not change
significantly compared to the one reported in ATel #881. The observed 0.5-5.0 keV flux
was 2.8x10^-12 erg s^-1 cm^-2 and the intrinsic source luminosity 3.5x10^38
erg s^-1 at a distance of 780 kpc.
From the region of the Be/X-ray transient candidate XMMU J004215.8+411924 just
three photons were recorded indicating a further decay by a factor of more than
5 with respect to the SWIFT observation 10 days earlier. This corresponds to an
upper limit for the 0.5-10.0 keV intrinsic source luminosity of
5x10^36 erg s^-1 assuming a similar spectrum as for the XMM-Newton detection.
We thank the Swift team for accepting and scheduling these target of opportunity
observations.