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Chandra observations of IGR J16316-4028

ATel #253; J. Rodriguez (CEA/SAp, France & ISDC Switzerland), L. Foschini (IASF, Italy), A. Goldwurm (CEA), V. Beckmann (GSFC, USA), K. Ebisawa (GSFC & ISDC)
on 19 Mar 2004; 13:34 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Jerome Rodriguez (jrodriguez@cea.fr)

Subjects: X-ray, Gamma Ray, Request for Observations, Binary, Black Hole, Nova, Neutron Star, Transient, Pulsar

We report on a Chandra Director Discretionary Time observation of the region around IGR J16316-4028 (see Rodriguez and Goldwurm Atel #201) performed on January 18, 2004, 13:01 UT. The analysis of HRC-I data did not reveal any significant (> 3sigma) excess in the field of view (30" X 30"), with an upper limit in flux of 5 10-14 erg.cm-2.s-1 in the 0.5-10 keV energy range.

We further report on the spectral analysis of the INTEGRAL/IBIS observation performed on February 28, 2003. The source had a power law like spectrum of photon index 2.7 (+0.2 -0.3 at 3 sigma) and an average 20-100 keV flux of 1.2 10-10 ergs.cm-2.s-1. This suggests that IGR J16316-4028 was flaring at the time of its discovery (extrapolated 0.5-10 keV flux of 2.3 10-9 ergs.cm-2.s-1), and was in quiescence during the Chandra observation. The planned scans of this sky region with INTEGRAL will possibly allow the source to be detected during future outburst/flares. The authors are grateful to H. Tananbaum for the generous and prompt allocation of DDT and to the CXC for the rapid data processing and delivery.