We report here an all-sky soft gamma-ray source catalog based on IBIS observations performed during the first 1000 orbits of INTEGRAL. The database for the construction of the source list consists of all good quality data available from launch in 2002 up to the end of 2010. This corresponds to ∼110 Ms of scientific public observations with a concentrated coverage on the Galactic Plane and extragalactic deep exposures. This new catalog includes 939 sources above a 4.5 sigma significance threshold detected in the 17-100 keV energy band, of which 120 represent previously undiscovered soft gamma-ray emitters. The source positions are determined, mean fluxes are provided in two main energy bands, and are reported together with the overall source exposure. Indicative levels of variability are provided, and outburst times and durations are given for transient sources. Comparison is made with previous IBIS catalogs, and those from other similar missions.1 Based on observations with INTEGRAL, an ESA project with instruments and science data centre funded by ESA member states (especially the PI countries:

We report the first high-energy survey catalog obtained with the IBIS gamma-ray imager on board INTEGRAL. The analysis has been performed on the first-year Core Program ISGRI data comprising both Galactic Plane Scan and Galactic Centre Deep Exposure pointings for a total exposure time exceeding 5 Ms. This initial survey has revealed the presence of ∼120 sources detected with the unprecedented sensitivity of ∼1 mcrab in the energy range 20-100 keV. Each source is located to an accuracy between 1Ј and 3Ј, depending on its brightness. The outstanding IBIS capability to locate soft g-ray emitters has allowed us to identify most of the detected sources with already known Galactic X-ray binary systems, while 28 of the objects are of unknown nature.

An analysis of the high-energy emission from IGR J16393−4643 (=AX J1639.0−4642) is presented using data from INTEGRAL and XMM-Newton. The source is persistent in the 20-40 keV band at an average flux of 5.1 × 10 −11 erg cm −2 s −1 , with variations in intensity by at least an order of magnitude. A pulse period of 912.0±0.1 s was discovered in the ISGRI and EPIC light curves. The source spectrum is a strongly-absorbed (N H = (2.5 ± 0.2) × 10 23 cm −2 ) power law that features a high-energy cutoff above 10 keV. Two iron emission lines at 6.4 and 7.1 keV, an iron absorption edge 7.1 keV, and a soft excess emission of 7 × 10 −15 erg cm −2 s −1 between 0.5-2 keV, are detected in the EPIC spectrum. The shape of the spectrum does not change with the pulse. Its persistence, pulsation, and spectrum place IGR J16393−4643 among the class of heavily-absorbed HMXBs. The improved position from EPIC is RA (J2000) = 16 h 39 m 05.4 s and Dec = −46 • 42 12 (4 uncertainty) which is compatible with that of 2MASS J16390535−4642137.

We present further results from our onging optical spectrophotometric campaign at the Astronomical Observatory of Bologna in Loiano (Italy) on unidentified hard X-ray sources detected by INTEGRAL. We observed spectroscopically the putative optical counterparts of the INTEGRAL sources IGR J00234+6141, IGR J01583+6713, IGR J06074+2205, IGR J13091+1137 and IGR J20286+2544. We find that the first two are Galactic objects, namely a Cataclysmic Variable at a distance d ∼ 300 pc and a Be/X transient High-Mass X-ray Binary (HMXB) located at ∼6.4 kpc, respectively, whereas the last one is identified with MCG +04-48-002, a Starburst/H ii galaxy at redshift z = 0.013 hiding a Seyfert 2 nucleus. We identify IGR J13091+1137 as the (likely Seyfert 2 type) active nucleus of galaxy NGC 4992, which we classify as an X-ray Bright, Optically Normal Galaxy; this is the first example of this type of object to be detected by INTEGRAL, and one of the closest of this class. We moreover confirm the possible Be/X nature of IGR J06074+2205, and we estimate it to be at a distance of ∼1 kpc. We also reexamine the spectrum of the z = 0.087 elliptical radio galaxy PKS 0352−686, the possible counterpart of the INTEGRAL source IGR J03532−6829, and we find that it is a BL Lac. Physical parameters for these sources are also evaluated by discussing our findings in the context of the available multiwavelength information. These identifications further stress the importance of INTEGRAL in the study of the hard X-ray spectrum of Active Galactic Nuclei, HMXBs and Cataclysmic Variables.

We report the onset of a large amplitude, statistically significant periodicity (∼46 d) in the Rossi X‐ray Timing Explorer/All Sky Monitor (RXTE/ASM) data of the prototype X‐ray burster 4U 1636‐53, the X‐ray flux of which has been gradually declining over the last 4 yr. This behaviour is remarkably similar to that observed in the neutron star low mass X‐ray binary (LMXB), KS 1731‐260, which is a long‐term transient. We also report on an INTEGRAL/IBIS observation of 4U 1636‐53 during its decline phase, and find that the hard X‐ray flux (20–100 keV) indicates an apparent anticorrelation with soft X‐rays (2–12 keV). We argue that 4U 1636‐53 is transiting from activity to quiescence, as occurred in KS 1731‐260. We also suggest that the variability during the X‐ray decline is the result of an accretion rate variability related to the X‐ray irradiation of the disc.