HEASARC Browse: List of INTEGRAL Catalogs

List of INTEGRAL Catalogs

Integral Mission Description

Integral Guest Observer Facility

This table contains 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 the launch of INTEGRAL 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 sources represent previously undiscovered soft gamma-ray emitters. The source positions are determined, mean fluxes are provided in two main energy bands, and these are both reported together with the overall source exposure. Indicative levels of variability are provided, and outburst times and durations are given for transient sources. In the reference paper, a comparison is made with previous IBIS catalogs and catalogs from other similar missions.

INTAGNCAT Catalog

The INTEGRAL mission provides a large data set for studying the hard X-ray properties of AGN and allows testing the unified scheme for AGN. This table contains some of the results from the analysis of INTEGRAL IBIS/ISGRI, JEM-X, and OMC data for 199 AGN (and 3 clusters of galaxies) that have been reported to be detected by INTEGRAL at energies above 20 keV. The data analyzed therein allowed a significant spectral extraction on 148 objects and optical variability study of 57 AGN. The slopes of the hard X-ray spectra of Seyfert 1 and Seyfert 2 galaxies were found to be consistent within the uncertainties, whereas lower luminosities were measured for the more absorbed/type 2 AGN. The intermediate Seyfert 1.5 objects exhibit hard X-ray spectra consistent with those of Seyfert 1 galaxies. When applying a Compton reflection model, the underlying continua appear still the same in Seyfert 1 and 2 with photon index 2, and the reflection strength is about R = 1, when assuming different inclination angles. A significant correlation is found between the hard X-ray and optical luminosity and the mass of the central black hole, in the sense that the more luminous objects appear to be more massive. There is also a general trend for the absorbed sources and type 2 AGN to have lower Eddington ratios. The black hole mass appears to form a fundamental plane together with the optical and X-ray luminosity of the form L_V being proportional to L_X^0.6 M_BH^0.2, similar to that found between radio luminosity L_R, L_X, and M_BH. The unified model for Seyfert galaxies seems to hold, showing in hard X-rays that the central engine is the same in Seyfert 1 and 2 but seen under different inclination angles and absorption.

A catalog of 199 IBIS/ISGRI detected AGN is presented. For those 148 objects significantly detected in the data set analyzed here, spectral parameters, fluxes, and luminosities are given. In addition, the photometric table of OMC measurements in the V-band (given for 57 of the AGN) is also included herein.

For objects with more complex spectra, notice, the results of a fit to a cut-off power law model were presented in Table 3 of the reference paper, but are not included in this HEASARC table. The JEM-X spectra of the 23 AGN detected by the X-ray monitor were fit with the IBIS/ISGRI data, and the results of this were presented in Table 4 of the reference paper, but are also not included in this HEASARC table.

INTBSC Catalog

The INTEGRAL Bright Source Catalog is based on publicly available data from the two main instruments (IBIS and SPI) on board INTEGRAL (see Winkler et al. 2003, A&A, 411, L1 for a description of the INTEGRAL spacecraft and instrument packages). INTEGRAL began collecting data in October 2002. This catalog will be regularly updated as data become public (~14 months after they are obtained).

The Bright Source Catalog is a collaborative effort between the INTEGRAL Science Data Center (ISDC) in Switzerland and the NASA Goddard Space Flight Center (GSFC) INTEGRAL Guest Observer Facility (GOF). The results presented here are a result of a semi-automated analysis and they should be considered as approximate: they are intended to serve as a guideline to those interested in pursuing more detailed follow-up analyses.

The data from the imager ISGRI (Lebrun et al. 2003, A&A, 411, L141) have been analyzed at the INTEGRAL Science Data Centre (ISDC), while the SPI (Vedrenne et al. 2003, A&A, 411, L63) data analysis was performed at GSFC as a service of the INTEGRAL GOF.

INTEGRALAO Catalog

This HEASARC database table contains the INTEGRAL pointed observing programs for AO-1 through AO-20 and includes targets in both the Core Program (Guaranteed Time) pointed observations list and in the General Program (Open Time) accepted observations list.

INTGCCAT Catalog

From August 23 through September 24, 2003, the INTEGRAL Observatory conducted a deep survey of the Galactic Center region with a record-breaking sensitivity at energies above 20keV. The authors analyzed the images of the Galactic Center region obtained with the ISGRI detector of the IBIS telescope (15 - 200 keV) and this table contains their catalog of detected sources. A total of 60 sources with fluxes above 1.5 milliCrab were detected in the range from 18 to 60 keV (1 mCrab = 1.36 x 10^-11 erg/s/cm^2 in this energy band for a source with a power-law spectrum with a photon index of 2.1) above a detection threshold of 6.5 sigma which was chosen to avoid the strong effect of systematic uncertainties. The nature of 51 of the 60 sources is known: most of them (38 of 51) are low-mass X-ray binaries, and the remaining 13 include 5 high-mass X-ray binaries, 2 cataclysmic variables, an anomalous X-ray pulsar, a soft gamma repeater and three extragalactic objects.

INTIBISAG2 Catalog

In the most recent IBIS survey based on observations performed during the first 1000 orbits of INTEGRAL, there are listed 363 high-energy emitters firmly associated with AGN, 107 of which are reported here for the first time. The authors have used X-ray data to image the IBIS 90% error circle of all the AGN in the sample of 107, in order to obtain the correct X-ray counterparts, locate them with arcsecond accuracy and therefore pinpoint the correct optical counterparts. This procedure has led to the optical and spectral characterization of the entire sample. This new set consists of 34 broad line or type 1 AGN, 47 narrow line or type 2 AGN, 18 blazars and 8 sources of unknown class. These eight sources have been associated with AGN from their positional coincidence with 2MASX/Radio/X-ray sources. Seven high-energy emitters have also been included since they are considered to be good AGN candidates. Spectral analysis has been already performed on 55 objects and the results from the most recent and/or best statistical measurements have been collected. For the remaining 52 sources, the authors report the spectral analysis for the first time in this work. They have been able to obtain full X-ray coverage of the sample making use of data from Swift/XRT, XMM-Newton and NuSTAR. In addition to the spectral characterization of the entire sample, this analysis has enabled the authors to identify peculiar sources and by comparing different data sets, highlight flux variability in the 2-10 keV and 20-40 keV bands.

In the reference paper, the authors present the X-ray and optical follow-up work on 107 new AGN recently detected by INTEGRAL. Fortunately, they have been able to obtain full X-ray coverage of the entire sample making use of data from the Swift/XRT, Newton-XMM, and NuSTAR archives or through Swift/XRT follow-up observations that they triggered.

The HEASARC notes that this table of AGN newly detected by INTEGRAL and not included in the original INTEGRAL IBIS AGN Catalog (Malizia et al. 2012, MNRAS, 426, 1750, available at the HEASARC as the INTIBISAGN table) actually contains 108 AGN plus 8 candidate AGN, for a total of 116 objects, rather than the 107 plus 7 candidate AGN totalling 114 objects that are quoted in the abstract of the reference paper (and stated above). The reason for this discrepancy is not known to the HEASARC.

INTIBISAGN Catalog

In this work, the authors present the most comprehensive INTEGRAL active galactic nucleus (AGN) sample. It lists 272 AGN for which they have secure optical identifications, precise optical spectroscopy and measured redshift values plus X-ray spectral information, i.e. 2-10 and 20-100 keV fluxes plus column densities. In their paper, the authors mainly use this sample to study the absorption properties of active galaxies, to probe new AGN classes and to test the AGN unification scheme. The authors find that half (48%) of the sample is absorbed, while the fraction of Compton-thick AGN is small (~7%). In line with their previous analysis, they have however shown that when the bias towards heavily absorbed objects which are lost if weak and at large distance is removed, as is possible in the local Universe, the above fractions increase to become 80% and 17%, respectively. The authors also find that absorption is a function of source luminosity, which implies some evolution in the obscuration properties of AGN. A few peculiar classes, so far poorly studied in the hard X-ray band, have been detected and studied for the first time such as 5 X-ray bright optically normal galaxies (XBONGs), 5 type 2 QSOs and 11 low-ionization nuclear emission regions. In terms of optical classification, this sample contains 57% type 1 and 43% type 2 AGN; this subdivision is similar to that found in X-rays if unabsorbed versus absorbed objects are considered, suggesting that the match between optical and X-ray classifications is on the whole good. Only a small percentage of sources (12%) does not fulfill the expectation of the unified theory as the authors find 22 type 1 AGN which are absorbed and 10 type 2 AGN which are unabsorbed. Studying in depth these outliers they found that most of the absorbed type 1 AGN have X-ray spectra characterized by either complex or warm/ionized absorption more likely due to ionized gas located in an accretion disc wind or in the bi-conical structure associated with the central nucleus, therefore unrelated to the toroidal structure. Among the 10 type 2 AGN which are unabsorbed, at most 3-4% are still eligible to be classified as 'true' type 2 AGN.

In the fourth INTEGRAL/IBIS survey (Bird et al. 2010, ApJS, 186, 1, available in the HEASARC database as the IBISCAT4 table), there are 234 objects which have been identified with AGN. To this set of sources, the present authors then added 38 galaxies listed in the INTEGRAL all-sky survey by Krivonos et al. (2007, A&A, 475, 775, available in the HEASARC database as the INTIBISASS table) updated on the website (http://hea.iki.rssi.ru/integral/survey/catalog.php) but not included in the Bird et al. catalog due to the different sky coverage (these latter sources are indicated with hard_flag = 'h' values in this HEASARC table). The final data set presented and discussed in the reference paper and constituting this table therefore comprises 272 AGN and was last updated in March 2011 March. It represents the most complete view of the INTEGRAL extragalactic sky as of the date of publication in 2012.

INTIBISASS Catalog

The INTEGRAL IBIS All-Sky Survey of Hard X-Ray Sources table contains the results from a paper which is the second in a series devoted to the hard X-ray (17 - 60 keV) whole sky survey which has been performed by the INTEGRAL observatory over its first seven years of observations. This table contains the catalog of detected sources and includes 521 objects, 449 of which exceed a 5-sigma detection threshold on the time-averaged map of the sky, and 53 which were detected in various sub-samples of exposures. Among the identified sources with known and suspected natures, 262 are Galactic (101 low-mass X-ray binaries, 94 high-mass X-ray binaries, 37 cataclysmic variables, and 30 of other types) and 221 are extragalactic, including 217 active galactic nuclei (AGNs) and 4 galaxy clusters. The extragalactic (|b| > 5 degrees) and Galactic (|b| < 5 degrees) persistently detected source samples have high identification completeness (respectively ~96% and ~93%) and are valuable for population studies.

The current INTIBISASS table is based on the data provided in Krivonos et al. (2010: Paper II below) and replaces the earlier version available at the HEASARC from February 2008 to December 2010 which was based on Krivonos et al. (2007).

INTIBISGAL Catalog

The INTEGRAL observatory operating in a hard X-ray/gamma domain has gathered a large observational data set over nine years starting in 2003. Most of the observing time was dedicated to the Galactic source population study, making possible the deepest Galactic survey in hard X-rays ever compiled.

The authors aimed to perform a Galactic survey that could be used as the basis of Galactic source population studies, and performed mapping of the Milky Way in hard X-rays over the maximum exposure available at Galactic latitudes |b| < 17.5 degrees. They used sky reconstruction algorithms especially developed for the high quality imaging of INTEGRAL/IBIS data. In their paper. they presented sky images, sensitivity maps, and catalogs of detected sources in the three energy bands 17 - 60, 17 - 35, and 35 - 80 keV in the Galactic plane at |b| < 17.5 degrees. The total number of sources in the reference 17 - 60 keV band includes 402 objects exceeding a 4.7-sigma detection threshold on the nine-year time-averaged map. Among the identified sources with known and tentatively identified natures, 253 are Galactic objects (108 low-mass X-ray binaries, 82 high-mass X-ray binaries, 36 cataclysmic variables, and 27 are of other types), and 115 are extragalactic objects, including 112 active galactic nuclei and 3 galaxy clusters. The sample of Galactic sources with S/N > 4.7 sigma has an identification completeness of ~92%, which is valuable for population studies. Since the survey is based on the nine-year sky maps, it is optimized for persistent sources and may be biased against finding transients.

This table contains the catalog of 402 INTEGRAL sources exceeding the detection threshold in the 17 - 60 keV energy band.

INTIBISVHD Catalog

This table contains results from an all-sky survey, performed by the Imager on-Board the INTEGRAL Satellite (IBIS) telescope on board the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observatory over 11 years of operation, using data acquired at energies above 100 keV. The catalog of detected sources includes 132 objects. The statistical sample detected on the time-averaged 100-150 keV map at a significance above 5 sigma contains 88 sources: 28 active galactic nuclei (AGNs), 38 low-mass X-ray binaries (LMXBs), 10 high-mass X-ray binaries (HMXBs) and 12 rotation-powered young X-ray pulsars. The catalog also includes 15 persistent sources, which were registered at a significance 4 sigma <= S/N < 5 sigma, where S/N is the signal-to-noise ratio, but at the same time were firmly detected (>= 12 sigma) in the lower 17-60 keV energy band. All registered sources are known X-ray emitters, which means that the catalog has 100% purity in this respect. Additionally, 29 catalogued sources were detected significantly in different time slices of the survey. In the reference paper presenting the results of this survey, the authors present a hardness ratio for Galactic and extragalactic sources, an LMXB longitudinal asymmetry, and a number-flux relation for non-blazar AGNs. At higher energies, in the 150-300 keV energy band, 25 sources have been detected with S/N >= 5 sigma, including seven AGNs, 13 LMXBs, three HMXBs and two rotation-powered pulsars. Among LMXBs and HMXBs, the authors identified 12 black hole candidates (BHCs) and four neutron star (NS) binaries.

For this hard X-ray survey, the authors utilized all publicly available INTEGRAL data acquired by the IBIS telescope between 2002 December and 2014 January (INTEGRAL spacecraft revolutions 26 - 1377). The survey also contains private data from the M82 deep field (PI: Sazonov) and scanning observations of the Galactic Center (PI: Krivonos) and Puppis region (PI: Tsygankov). The survey sky coverage as a function of a 5-sigma limiting flux is shown in Fig. 2 of the reference paper. The peak sensitivity of the survey is about 2 mCrab (8 x 10^-12 erg s^-1 cm^-2 in the 100-150 keV energy band). The survey covers ~10% of the sky down to a flux limit of 3.7 mCrab (1.5 x 10^-11 erg s^-1 cm^-2) and 90% of the sky down to 25 mCrab (10^-10 erg s^-1 cm^-2).

The catalog has been compiled from sources passed through detection conditions in the reference 100-150 keV energy band on time-average sky maps (Section 2.1 of the reference paper) and maps built over different time periods (Section 2.2 ibid.). For all 132 sources, the time-averaged fluxes are given, even for those sources which were not detected therein. For some variable sources and for sources which were only detected in certain time periods, the fluxes measured in the specified time intervals are also given. Thus, this catalog has 50 additional rows for such entries, giving it a total size of 182 rows.

INTOMCVS Catalog

The Optical Monitoring Camera (OMC) on board the high-energy INTEGRAL satellite provides photometry in the Johnson V-band within a 5 by 5 degree field of view. The OMC is able to detect optical sources brighter than around V ~ 18, from a previously selected list of potential targets of interest. After more than nine years of observations, the OMC database contains light curves for more than 70 000 sources (with more than 50 photometric points each). The objectives of the present work have been to characterize the potential variability of the objects monitored by OMC, to identify periodic sources and to compute their periods, taking advantage of the stability and long monitoring time of the OMC.

The first catalog of variable sources observed by OMC has been developed with observations from October 2002 to February 2010. To detect potential variability, the authors have performed a chi-squared test, finding 5263 variable sources, for 1337 of which the periods have been determined, out of an initial sample of 6071 objects with good photometric quality and more than 300 data points each. They have studied the potential periodicity of these sources using a method based on the phase dispersion minimization technique, optimized to handle light curves with very different shapes. For each object in the catalog, the median of the visual magnitude, the magnitude at maximum and minimum brightness in the light curve during the window of observations and the period, when found, are provided. The types of variable objects in the catalogue include eclipsing binaries, pulsating stars, rotating stars, eruptive stars, extragalactic objects, X-ray binaries, cataclysmic variables, Be stars and other objects with unknown kinds of variability.

Links to charts for each object, including the DSS image around the target, the unfolded and folded light curves with the periods that the authors have derived and/or with the cataloged ones are provided in this database.

INTPUBLIC Catalog

The INTEGRAL Public Data Results Catalog is based on publicly available data from the two main instruments (IBIS and SPI) on board INTEGRAL (see Winkler et al. 2003, A&A, 411, L1 for a description of the INTEGRAL spacecraft and instrument packages). INTEGRAL began collecting data in October 2002. This catalog will be regularly updated as data become public (~14 months after they are obtained).

This catalog is a collaborative effort between the INTEGRAL Science Data Center (ISDC) in Switzerland and the NASA Goddard Space Flight Center (GSFC) INTEGRAL Guest Observer Facility (GOF). The results presented here are a result of a semi-automated analysis and they should be considered as approximate: they are intended to serve as a guideline to those interested in pursuing more detailed follow-up analyses.

Note: For cases where two or more proposals have been amalgamated (entries with pi_lname = 'Amalgamated') for a given observation, the same observation is listed for each of the amalgamated proposal numbers.

INTREFCAT Catalog

The original version of the INTEGRAL Reference Catalog as published in 2003 classified previously known bright X-ray and gamma-ray sources before the launch of INTEGRAL. These sources are, or have been at least once, brighter than ~1 milliCrab above 3 keV energy, and are expected to be detected by INTEGRAL. This catalog was used in the INTEGRAL Quick Look Analysis (QLA) to discover new sources or significantly variable sources. The authors compiled several published X-ray and gamma-ray catalogs, and surveyed recent publications for new sources. Consequently, there were 1121 sources in the original INTEGRAL Reference Catalog. In addition to the source positions, an approximate spectral model and expected flux were given for each source, and the expected INTEGRAL counting rates based on these parameters was derived. Assuming the default instrument performances and at least ~10⁵ seconds exposure time for any part of the sky, it is expected that INTEGRAL will detect at least ~700 sources below 10 keV and ~400 sources above 20 keV over the mission life.

After the launch of INTEGRAL, a version of this catalog was placed on the ISDC website at http://www.isdc.unige.ch/integral/science/catalogue and has been updated periodically since then by adding, for example, new sources discovered by INTEGRAL itself (indicated by the IGR prefix in the name). This HEASARC table is based on the web version at the ISDC, and will be updated within a few days of whenever the latter is updated.

INTSCW Catalog

Because of the pointing-slew-pointing dithering-nature of INTEGRAL operations, each observation of a celestial target is actually comprised of numerous individual S/C pointings and slews. In addition, there are periods within a given sequence where scheduled observations occur, i.e., engineering windows, yet the instruments still acquire data. The INTEGRAL Science Data Center (ISDC) generalizes all of these data acquisition periods into so-called `Science Windows.'

A Science Window (ScW) is a continuous time interval during which all data acquired by the INTEGRAL instruments result from a specific S/C attitude orientation state. Pointing (fixed orientation), Slew (changing orientation), and Engineering (undefined orientation) windows are all special cases of a Science Window. The key is that the same attitude information may be associated with all acquired data of a given Science Window. Note that it is possible to divide a time interval that qualifies as a Science Window under this definition into several smaller Science Windows using arbitrary criteria.

The INTEGRAL Science Window Data Catalog allows for the keyed search and selection of sets of Science Windows and the retrieval of the corresponding data products.

INTSCWPUB Catalog

The INTEGRAL Public Pointed Science Window Data Catalog is a subset of the INTEGRAL Science Window Data Catalog. It only includes pointed science windows that have non-private proprietary status and at least one instrument's "good" exposure time greater than zero.

INTSPIAGRB Catalog

The First INTEGRAL SPI-ACS Gamma-Ray Burst (GRB) Catalog contains the sample of gamma-ray bursts detected with the Anti-Coincidence Shield (ACS) of the SPI spectrometer on-board the INTEGRAL spacecraft for the first 26.5 months of mission operations (up to January 2005). The SPI-ACS works as a nearly omnidirectional gamma-ray burst detector above ~80 keV, but it lacks spatial and spectral information. In this catalog, the properties derived from the 50 millisecond (ms) light curves (e.g., T_90, C_max, C_int, variability, and V/V_max) are given for each candidate burst in the sample. A strong excess of very short events with durations < 0.25 seconds is found. This population is shown to be significantly different from the short- and long-duration burst sample by means of the intensity distribution and the V/V_max test and is certainly connected with cosmic ray hits in the detector. A rate of 0.3 true gamma-ray bursts per day is observed.

This table lists the properties of 388 GRB candidates detected from Oct 27, 2002 to Jan 15, 2005 with the Anti-Coincidence Shield (ACS) of SPI. It has numerous events with missing entries, notice. For all GRBs which were confirmed by other instruments but were detected by SPI-ACS below the sample selection threshold, only the time, date, significance and common instruments are listed. Furthermore, the variability measure was obtained only for long-duration events which had sufficiently large signal-to-noise ratios.

INTVARCAT Catalog

In 6 years of operation, INTEGRAL/ISGRI revealed more than 500 sources. Many of these sources are variable. Taking into account that nearly half of INTEGRAL/ISGRI sources are new and many of them are still unidentified, the variability properties of the sources can serve as additional parameters that may help to classify and identify the unknown sources. In order to study the variability properties of the sources detected by INTEGRAL/ISGRI, the authors have developed a method to quantify the variability of a source which is described in their paper. They have compiled a catalog of the sources that fit their criteria of variability.

This catalog gives the values of fractional variability, the flux, and the corresponding 2-sigma errors of the sources from the INTEGRAL Reference Catalog (CDS Cat. J/A+A/411/L59: INTVARCAT in Browse) version 30. The data are given for 3 energy bands: 20-40, 40-100, and 100-200 keV. The exposure times of the sources are given for each energy band only if the source was detected in the given band. This table also gives the source type according to the reference catalog. If the source is localized in more then one map then the weighted mean values of the flux and variability are given. The sources active during specific time periods and not detected at the total variability map are indicated with "b" letter in the source_flag parameter. The sources detected only in the total variability map are indicated with an "i" letter value for this parameter, while a letter "g" indicates that the source was affected by the "ghost" of another source. The map_det* parameters specify the time period map(s) in which the source was visible, where the presence of an 'X' following a map number means that the source was not detected in the respective significance map, and that a lower limit for the fractional variability is given in such a case.

ISGRI4YRCT Catalog

In its first 4 years of observing the sky above 20 keV, the INTEGRAL Soft Gamma-ray Imager (ISGRI) detected ~ 500 sources, around half of which were new or unknown at these energies. Follow-up observations at other wavelengths revealed that some of these sources feature unusually large column densities, long pulsations, and other interesting characteristics. The authors investigated where new and previously-known sources detected by ISGRI fit in the parameter space of high-energy objects, and they used the parameters to test correlations expected from theoretical predictions. For example, the influence of the local absorbing matter on periodic modulations was studied for Galactic High-Mass X-ray Binaries (HMXBs) with OB supergiant and Be companions. In their paper, they examined the spatial distribution of different types of sources in the Milky Way, using various projections of the Galactic plane, in order to highlight signatures of stellar evolution and to speculate on the origin of the group of sources whose classifications were still uncertain.

This table contains all 499 sources detected by ISGRI listed in the reference paper, with the exception of the source 'PSR B1841-04' which was removed from the electronic version of the table by the CDS, after discussion with the author. The table contains the most precise coordinates and error radii available in the literature. Classifications are provided for all sources. When available, the published photoelectric absorption in the X-rays, distances/redshifts, and pulsation and orbital periods are also listed.

SIXSRVYCAT Catalog

The supermassive black holes at the center of active galactic nuclei (AGNs) are surrounded by obscuring matter that can block nuclear radiation. Depending on the amount of blocked radiation, the flux from the AGN can be too faint to be detected by currently operating hard X-ray (above 15 keV) missions. At these energies, only ~1% of the intensity of the cosmic X-ray background (CXB) can be resolved into point-like sources that are AGNs. In this work, the authors address the question of undetected sources contributing to the CXB with a very sensitive and new hard X-ray survey: the Swift-INTEGRAL X-ray (SIX) survey, which is obtained with the new approach of combining the Swift/BAT and INTEGRAL/IBIS X-ray observations. The authors merge the observations of both missions, which enhances the exposure time and reduces systematic uncertainties. As a result, they obtain a new survey over a wide sky area of 6200 deg² covering the region of the North Ecliptic Pole (NEP) and extending to the contiguous Coma region that is more sensitive than the surveys of Swift/BAT or INTEGRAL/IBIS alone. Their sample comprises 113 sources having S/N ratios of above 4.8 sigma: 86 AGNs (Seyfert-like and blazars), 5 galaxies, 2 clusters of galaxies, 3 Galactic sources, 3 previously detected unidentified X-ray sources, and 14 unidentified sources. The scientific outcome from the study of the sample has been properly addressed to study the evolution of AGNs at a redshift below 0.4. The authors do not find any evolution using the 1/V_max method. Their sample of faint sources is a suitable target for the new generation of hard X-ray telescopes with focusing techniques.

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