SAX J1808.4-3658 is in Outburst Again
ATel #505; C. B. Markwardt (U. Maryland & NASA/GSFC), J. Swank (NASA/GSFC), R. Wijnands (U. Amsterdam), J. in 't Zand (SRON)
on 1 Jun 2005; 17:27 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Craig B. Markwardt (craigm@lheamail.gsfc.nasa.gov)
Subjects: X-ray, Request for Observations, Binary, Neutron Star, Transient, Pulsar
RXTE PCA Bulge scans on May 31, 23h UTC, indicate that a source
consistent with the position of SAX J1808.4-3658 has entered outburst.
The previous outburst of J1808 was in October 2002, and this outburst
would be consistent with the approximate recurrence period of ~2
years. The 2-10 X-ray flux was approximately 3 mCrab.
A small amount of high time resolution data was available (~150
seconds). The expected 401 Hz pulsations were not detected in a
straight un-barycentered FFT, with a 95% confidence upper limit of
~25% r.m.s. This does not rule out the identification of SAX
J1808.4-3658, since the pulsation amplitude is typically ~5%.
More RXTE observations are planned.
