New outburst of XTE J1739-285 detected by INTEGRAL/JEM-X
ATel #13138; I. A. Mereminskiy, S. A. Grebenev (Space Research Institute, Russian Academy of Sciences)
on 27 Sep 2019; 14:57 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Sergei Grebenev (sergei@hea.iki.rssi.ru)
Subjects: X-ray, Request for Observations, Neutron Star
During the new run of INTEGRAL Galactic Center observations started on Sep. 27, 2019,
at 6:57 UTC we detected an X-ray outburst of the transient LMXB source harboring one
of the fastest rotating neutron star yet known (its spin frequency was measured to be
1122 Hz). The source is also known as an X-ray burster. The transient was last observed
in the active state in 2013 (ATEL #4804).
At the moment, its outburst was detected by only the JEM-X X-ray monitor on board INTEGRAL
that indicates its softness. The 3-12 keV flux from the source was estimated to be 34+/-4 mCrab.
The source was not detected in our previous observing run of the region, on Sept. 24-25,
when the 5 sigma upper limit for its flux in the same band was obtained to be 10 mCrab.
Given the peculiarity of the source we are strongly encourage follow-up observations at
all wavelengths. INTEGRAL will continue to monitor the Galactic Center region in the
upcoming weeks.
