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IGR J01583+6713, a new hard X-ray transient discovered by INTEGRAL

ATel #672; C. Steiner, D. Eckert, N. Mowlavi (ISDC, Geneva), A. Decourchelle (CEA, Saclay), J. Vink (SRON, Netherlands)
on 12 Dec 2005; 11:49 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Nami Mowlavi (Nami.Mowlavi@obs.unige.ch)

Subjects: X-ray, Request for Observations, Transient

Referred to by ATel #: 673, 681

A new hard X-ray transient has been discovered by the IBIS/ISGRI imager on board INTEGRAL during an open-program observation of the Cas A region on 2005 Dec. 6-7. The new source was observed at RA=29.57, DEC=+67.22 deg with an uncertainty of 2 arcmin. Although it is not detected in individual Science Windows, the source is clearly seen in the 130 ksec mosaic image of the observation, with a mean flux of about 14 mCrab and a detection significance of 13 sigma in the 20-40 keV band. The source is not detected in the 40-80 keV band, with an upper limit of about 7 mCrab. The source was always outside of the JEM-X field of view.
The field was observed again by INTEGRAL/ISGRI during the next revolution, on Dec. 8-10. The flux of IGR J01583+6713 in the 20-40 keV mosaic image of the first 50 ksec of the observation is about 11 mCrab with a significance of 8 sigma. In the mosaic of the rest of the revolution (150 ksec), the flux decreased to about 8 mCrab with a significance of 5.5 sigma. The flux of IGR J01583+6713 is thus decreasing on a time scale of days.
No X-ray counter part is reported in Simbad within the ISGRI error circle. The closest known X-ray source is 1RXS J015918.4+671807, at a distance of 7.7 arcmin from IGR J01583+6713. Follow-up observations of this new transient is strongly encouraged at all wavelength.