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|Optical identification of IGR J13091+1137 as a heavily obscured AGN|
In order to identify the nature of the active nucleus of spiral galaxyNGC 4992, associated with the Chandra andINTEGRAL high-energy sources CXOU J130905.6+113803and IGR J13091+1137 (see Halpern, Atel #572 and Sazonov et al., 2005,A&A, 444, L37), we acquired a 15-minute optical spectrum on February1, 2006 with the instrument BFOSC mounted on the `G.D. Cassini' 1.5mtelescope of the Astronomical Observatory of Bologna located in Loiano(Italy).
|Unveiling the nature of INTEGRAL objects through optical spectroscopy. IV. A study of six new hard X-ray sources|
We present further results from our onging optical spectrophotometriccampaign at the Astronomical Observatory of Bologna in Loiano (Italy) onunidentified hard X-ray sources detected by INTEGRAL. We observedspectroscopically the putative optical counterparts of the INTEGRALsources IGR J00234+6141, IGR J01583+6713, IGR J06074+2205, IGRJ13091+1137 and IGR J20286+2544. We find that the first two are Galacticobjects, namely a Cataclysmic Variable at a distance d 300 pc anda 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, aStarburst/H ii galaxy at redshift z = 0.013 hiding a Seyfert 2 nucleus.We identify IGR J13091+1137 as the (likely Seyfert 2 type) activenucleus of galaxy NGC 4992, which we classify as an X-ray Bright,Optically Normal Galaxy; this is the first example of this type ofobject 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 weestimate it to be at a distance of ~1 kpc. We also reexamine thespectrum of the z = 0.087 elliptical radio galaxy PKS 0352-686, thepossible counterpart of the INTEGRAL source IGR J03532-6829, and we findthat it is a BL Lac. Physical parameters for these sources are alsoevaluated by discussing our findings in the context of the availablemultiwavelength information. These identifications further stress theimportance of INTEGRAL in the study of the hard X-ray spectrum of ActiveGalactic Nuclei, HMXBs and Cataclysmic Variables.
|Chandra and Optical Identification of INTEGRAL Sources|
Using public Chandra Director's DiscretionaryTime observations obtained in 2005 June-July of unidentified,high-latitude INTEGRAL sources that were suspected to be obscured AGN (PI: R. Sunyaev), I report their basic properties from the ACIS-Iimages, and optical counterparts from the Digitized Sky Survey. In eachcase, the brightest source in the Chandra image is chosen as the likely identification.
|Identification of 8 INTEGRAL hard X-ray sources with Chandra|
We report the results of identification of 8 hard X-ray sourcesdiscovered by the INTEGRAL observatory during the ongoing all-skysurvey. These sources have been observed by Chandra. In 6 cases a brightX-ray source was found within the INTEGRAL localization region, whichpermitted to unambiguously identify 5 of the objects with nearbygalaxies, implying that they have an active galactic nucleus (AGN),whereas one source is likely an X-ray binary in LMC. 4 of the 5 newlydiscovered AGNs have measured redshifts in the range 0.025-0.055. TheX-ray spectra reveal the presence of significant amounts of absorbinggas (NH in the range 1022-1024cm-2) in all 5 AGNs, demonstrating that INTEGRAL is startingto fill in the sample of nearby obscured AGNs.
|Arcsecond Positions of UGC Galaxies|
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
|Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies|
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.
|An image database. II. Catalogue between δ=-30deg and δ=70deg.|
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
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