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In this paper we report on the third soft gamma-ray source catalog obtained with the IBIS/ ISGRI gamma-ray imager on board the INTEGRAL satellite. The scientific data set is based on more than 40 Ms of high-quality observations performed during the first 3.5 yr of Core Program and public IBIS/ ISGRI observations. Compared to previous IBIS/ISGRI surveys, this catalog includes a substantially increased coverage of extragalactic fields, and comprises more than 400 high-energy sources detected in the energy range 17Y100 keV, including both transients and faint persistent objects that can only be revealed with longer exposure times.

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Fast X-ray Transients (FXTs) are believed to be non-recurrent bright X-ray sources lasting less than a day and occuring at serendipitous positions, they can best be detected and discovered by instruments having a sufficiently wide field of view and high sensitivity. The IBIS/ISGRI instrument onboard INTEGRAL is particularly suited to detect new or already known fast X-ray transient sources. We report on IBIS/ISGRI detection of newly discovered outbursts of three fast transient sources located at low Galactic latitude: SAX J1818.6−1703; IGR J16479−4514; IGR J17391−302/XTE J1739−302. The reported results confirm and strengthen the very fast transient nature of these sources, given that all their newly detected outbursts have a duration less than ∼3 h. Additionally, they provide the first evidence for a possible recurrent fast transient behaviour as all three sources were detected in outburst by ISGRI more than once during the last 2 years.

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.

In this paper we report the second soft gamma-ray source catalog obtained with the IBIS/ ISGRI gamma-ray imager on board the INTEGRAL satellite. The scientific data set is based on more than 10 Ms of high-quality observations performed during the first 2 years of Core Program and public IBIS/ISGRI observations, and covers $50% of the whole sky. The main aim of the first survey was to scan systematically, for the first time at energies above 20 keV, the whole Galactic plane to achieve a limiting sensitivity of $1 mcrab in the central radian. The target of the second year of the INTEGRAL mission lifetime was to expand as much as possible our knowledge of the soft gamma-ray sky, with the same limiting sensitivity, to at least 50% of the whole sky, mainly by including a substantial coverage of extragalactic fields. This catalog comprises more than 200 high-energy sources detected in the energy range 20-100 keV, including new transients not active during the first year of operation, faint persistent objects revealed with longer exposure time, and several Galactic and extragalactic sources in sky regions not observed in the first survey. The mean position error for all the sources detected with significance above 10 is $40 00 , enough to identify most of them with a known X-ray counterpart and to unveil the nature of most of the strongly absorbed ones, even though they are very difficult to detect in X-rays.

Context. IGR J18483−0311 is a poorly known transient hard X-ray source discovered by INTEGRAL during observations of the Galactic Center region performed between 23-28 April 2003. Aims. To detect new outbursts from IGR J18483−0311 using INTEGRAL and archival Swift XRT observations and finally to characterize the nature of this source using the optical/near−infrared (NIR) information available through catalogue searches. Methods. We performed an analysis of light curves and spectra of INTEGRAL and archival Swift XRT data as well as of optical/NIR catalogues. Results. We report on 5 newly discovered outbursts from IGR J18483−0311 detected by INTEGRAL. For two of them it was possible to constrain a duration of the order of a few days. The strongest outburst reached a peak flux of ∼120 mCrab (20-100 keV); its broad band JEM-X/ISGRI spectrum (3-50 keV) is best fitted by an absorbed cutoff power law with Γ=1.4±0.3, cutoff energy of 22 +7.5 −4.5 keV and N H =9 +5 −4 ×10 22 cm −2 . Timing analysis of INTEGRAL data allowed us to identify periodicities of 18.52 days and 21.0526 seconds which are likely the orbital period of the system and the spin period of the X-ray pulsar respectively. Swift XRT observations of IGR J18483−0311 provided a very accurate source position which strongly indicates a highly reddened star in the USNO-B1.0 and 2MASS catalogues as its possible optical/NIR counterpart. Conclusions. The X-ray spectral shape, the periods of 18.52 days and 21.0526 seconds, the high intrinsic absorption, the location in the direction of the Scutum spiral arm and the highly reddened optical object as possible counterpart, all favour the hypothesis that IGR J18483−0311 is a HMXB with a neutron star as compact companion. The system is most likely a Be X-ray binary, but a Supergiant Fast X-ray Transient nature can not be entirely excluded.