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IGR J17091-3624

ATel #149; E. Kuulkers (ESA/ESTEC), A. Lutovinov (IKI, Moscow), A. Parmar (ESA/ESTEC), F. Capitanio (IAS, Roma), N. Mowlavi (ISDC), W. Hermsen (SRON, Utrecht)
on 19 Apr 2003; 16:56 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: A.Lutovinov (aal@hea.iki.rssi.ru)

Subjects: X-ray, Gamma Ray, Request for Observations, Transient

Referred to by ATel #: 150, 152, 160, 444, 1140, 3144, 3150, 3916

We report the discovery of a new transient source with the IBIS/ISGRI detector onboard the INTEGRAL observatory, which we designate as IGR J17091-3624. The source position is RA=17h09.1m and DEC=-36o24m38s (equinox J2000, uncertainty ~3').

The source was first seen during a pointed observation between UT 2003 April 14 00:20 and April 15 06:12 with a flux of about 20 mCrab in the 40-100 keV energy band. The source was not evident in the 15-40 keV band with an upper limit of about 10 mCrab, and shows the source exhibited a hard spectrum at that time. During subsequent pointings of the Galactic Center Deep Exposure between UT 2003 April 15 14:25 and April 16 09:06 the source flux had increased to about 40 mCrab and 25 mCrab in the 15-40 and 40-100 keV band, respectively, showing a considerable softening of the source spectrum.

The source did not appear in both energy bands in a pointed observation a week earlier (UT 2003 April 6 15:41 - April 7 14:20), with upper limits of typically ~10 mCrab.

We encourage follow up observations at various wavelengths.