INTEGRAL observations of SGR 1833-0832: The detection of the prompt emission and the non-detection of soft gamma-rays in the post-burst era
ATel #2509; L. Kuiper (SRON), W. Hermsen (SRON, UvA)
on 25 Mar 2010; 13:13 UT
Credential Certification: Lucien Kuiper (L.M.Kuiper@sron.nl)
Subjects: X-ray, Gamma Ray, Neutron Star, Soft Gamma-ray Repeater, Transient, Pulsar
INTEGRAL observed the Scutum region around Galactic longitude L=25 at the time of
a burst from a source dubbed SGR 1833-0832 (GCN's #10526,#10530;#10536; ATEL #2493).
The source off-axis angle was about 5.7 degrees, just outside the fully coded field of view
of the Soft Gamma-Ray Imager ISGRI aboard INTEGRAL.
In the detector light curve of ISGRI data for the 20-150 keV band the short duration
burst (about 16 ms; GCN #10526) was clearly detected at time 18:35:57.07 TT, March 19, 2010
(=18:34:50.9 UTC, March 19, 2010) and thus coincident with the Swift BAT trigger time.
Its significance is about 19 sigma (about 64 counts were collected during a 0.02 s time interval
of which 8 counts are expected to be background; see http://www.sron.nl/~kuiper/ATEL/SGR1833-0832
for the ISGRI 20-150 keV detector light curve in 0.01 s time bins).
The sky region near SGR 1833-0832 was again in the INTEGRAL field of view for about 45 ks
from March 20, 2010 10:22 till March 21, 2010 00:00 and for about 90 ks from March 21, 2010 10:30
till March 23, 2010 05:39. Imaging analysis of the ISGRI data for the combined data set (136.38 ks
of total good time exposure) yielded no detection of SGR 1833-0832 at energies above 20 keV.
We obtained a 3 sigma flux upper limit of 2 mCrab in the 20-60 keV band.