Search

A general catalog of active galactic nuclei (AGN) has been created from identified optical sources of X-ray data from the Hamburg-ROSAT Catalog (HRC) and the Byurakan-Hamburg ROSAT Catalog (BHRC). Optical and multiwavelength data from both catalogs have been examined in order to eliminate erroneous AGN and add new ones. The result is a new catalog of 4253 AGN with X-ray emission (ROSAT BSC/FSC). All of these sources are either AGN or have been classified as candidates. All the multiwave data (gamma, X-ray, UV, optical, IR, radio) have been retrieved for these objects using new catalogs and statistical studies have been made. Attempts have been made to find the relation between the radiative fluxes in different ranges for various types of sources and to determine their characteristics, thereby confirming their membership as AGN. The X-ray properties of these sources have been analyzed in order to find the boundary between normal galaxies and X-ray AGN, and an attempt has been made to find hidden AGN.

This is a detailed spectral classification of 96 active galaxies from the Veron-Cetty and Veron catalog (2010, Version 13, VCV-13) of active galaxies and quasars. These objects were identified as radio sources using standard radio catalogs. Those galaxies which had radio sources in at least 6 different radio bands and had been identified spectrally in the SDSS catalog were selected. The types of activity of these were determined using their SDSS spectra. Three diagnostic diagrams and a direct study of the spectra were used for more certain classification. As a result, the classifications of 85% of the objects were changed. The radio sources in different radio bands make it possible to construct the spectral distribution of the energy in the radio range and to compare it with the optical activity types.

This is a detailed spectral classification of 198 candidate active galactic nuclei (AGN) from a joint HRC/BHRC sample consisting of a combination of the HRC (Hamburg-ROSAT) and BHRC (Byurakan-ROSAT) catalogs. These objects have been identified as optical counterparts of ROSAT x-ray sources, but spectra for 198 of them are given in the SDSS without determinations of their spectral classification. They are studied using the SDSS spectra and detailed types of activity are found for them. For a more reliable classification, three diagnostic diagrams have been used, along with direct studies of the spectra. These sources were also identified in other wavelength ranges and their physical parameters have also been calculated.

The Astrophysical Virtual Observatories (AVOs) have been created in a number of countries using their available databases and current observing material as a collection of interoperating data archives and software tools to form a research environment in which complex research programs can be conducted. Among all these data, a large spectroscopic database for all objects is especially useful. The Armenian Virtual Observatory (ArVO) has being created to utilize the Digitized First Byurakan Survey (DFBS) as an appropriate spectroscopic database. ArVO is a project of the Byurakan Astrophysical Observatory (BAO) aimed at construction of a modern system for data archiving, extraction, acquisition, reduction, use and publication. ArVO is based on DFBS and is the Armenian contribution to the International Virtual Observatories Alliance (IVOA). One of the ArVO's main tasks is to create and utilize a global Spectroscopic Virtual Observatory, which will combine data from DFBS and other low-dispersion spectroscopic databases, as well as provide the first understanding on the nature of any object up to B=18 m. In frame of ArVO, BAO collaborates with the Institute of Informatics and Automation Problems (IIAP) of the Armenian National Academy of Sciences to develop software for ArVO corresponding to the IVOA standards. Beside the DFBS, ArVO is being complemented by the Digitized Second Byurakan Survey (SBS) database, the Byurakan photographic archive, and BAO 2.6m and 1m Schmidt telescope observations, and will be a part of IVOA.

Bright IR galaxies (LIRG, ULIRG, and HLIRG) are important for research on star formation processes in the early universe since they can be detected at large distances owing to their luminosity. High IR is indicative of active star formation and starburst (SB) processes, which are typical of HII regions. In many cases high IR is indicative of an active galactic nucleus (AGN). This raises the question of whether the SB causes the AGN or vice versa, or is there no direct interaction? Given that these objects are very often binary or multiple systems, it is also interesting to study the interrelations among SB, nuclear activity of the members of a system, and their interactions or mergers. With cross correlation of the IRAS PSC/FSC Combined Catalog and SDSS DR14, 114 ultrabright IR galaxies have been indentified and classified with respect to their types of activity. 1 BLL, 2 quasars, 29 Seyfert types 1.0-1.8, 5 Seyfert type 2, 14 LINERS, 36 HII regions, and 14 objects with composite spectra (Composites) have been identified and classified. Among the type 1 Seyfert galaxies there are many objects with narrow lines.

A total of 18 lists of the First Byurakan Survey of Late-Type Stars (FBS LTS) were published between 1990 and 2016. The stars were found on FBS low-dispersion spectroscopic plates. A systematic search and selection were carried out on a surface of ∼16 000 deg2 on almost the whole area of the FBS. As a result, the ‘Revised and Updated Catalogue of the First Byurakan Survey of Late-Type Stars’ was generated (FBS LTS v1; 1045 objects). We present the second version of the catalogue of FBS LTS with new data (FBS LTS v2), comprising 1471 objects. It is a homogeneous and complete data base for high-Galactic-latitude, late-type stars, including M and C types. Since 2007, all FBS low-resolution spectral plates have been digitized. All digitized FBS (DFBS) spectral plates have been analysed with FITSView and SAO Image ds9, and numerous relatively faint LTSs have been discovered. We have performed cross-correlations with DFBS, USNO-B1.0, 2MASS, AllWISE, IRAS PSC/FSC, AKARI, ROSAT BSC/FSC, GCVS, SDSS and added updated SIMBAD data. For numerous new detected objects, we present accurate DSS2 positions, approximate spectral subtypes refined from the DFBS low-dispersion spectra, luminosity classes estimated from 2MASS colours, and available proper motions for 1471 FBS LTSs. The Revised and Updated Catalogue v2 lists a large number of completely new objects, which promises to extend very significantly the census of M giants, faint N-type asymptotic giant branch carbon stars, CH-type carbon giants at high Galactic latitudes, and M dwarfs in the Solar vicinity up to 16.0–17.0 mag in the visual. Some important data from Gaia DR2 and supplementary spectra from the Byurakan Astrophysical Observatory 2.6-m and LAMOST telescopes are presented.

In the present study we have cross-correlated NVSS and FIRST radio catalogues having radio flux measurements at the same 1.4 GHz frequency. This way we benefit from repeated observations from both catalogues, as they give more accurate positions and fluxes and more important, reveal large differences between the two measured fluxes, thus allowing to establish radio variability. As a result 79,382 radio variables have been revealed, including 6301 with flux differences at 1.4 GHz larger than 15 mJy, 1917 with flux differences > 45 mJy and 260 with flux differences > 200 mJy. By using a special technique (Mickaelian & Sinamyan 2010, Mickaelian et al. 2011), 2425 optically variable objects out of 6301 radio sources have been revealed. 2425 radio sources with both high radio and optical variability into four categories have been divided. 1206 (19%) out of 6301 radio sources have activity types from available catalogues and 619 (25.5%) out of 2425 radio sources with at the same time radio and optical variability have activity types from available catalogues. In addition, 279 radio sources out of 2425 have high variability in optical range. We have established their activity types when available. The IR fluxes and colours for the 6301 variable radio sources have been studied. Colour–colour diagrams show that most of the “unknown” sources are galaxies. The activity types for 110 (42%) out of 260 extremely high variable radio sources also have been retrieved.

The Byurakan Astrophysical Observatory (BAO) has always been one of the centres for surveys and studies of active galaxies. Here we review our search and studies of active galaxies during last 30 years using various wavelength ranges, as well as some recent related works. These projects since late 1980s were focused on multiwavelength search and studies of AGN and Starbursts (SB). 1103 blue stellar objects (BSOs) on the basis of their UV-excess were selected using Markarian Survey (First Byurakan Survey, FBS) plates and Markarian’s criteria used for the galaxies. Among many blue stars, QSOs and Seyfert galaxies were found by follow-up observations. 1577 IRAS point sources were optically identified using FBS lowdispersion spectra and many AGN, SB and high-luminosity IR galaxies (LIRG/ULIRG) were discovered. 32 extremely high IR/opt flux ratio galaxies were studies with Spitzer. 2791 ROSAT FSC sources were optically identified using Hamburg Quasar Survey (HQS) lowdispersion spectra and many AGN were discovered by follow-up observations. Fine analysis of emission line spectra was carried out using spectral line decomposition software to establish true profiles and calculate physical parameters for the emitting regions, as well as to study the spectral variability of these objects. X-ray and radio selection criteria were used to find new AGN and variable objects for further studies. We have estimated AGN content of X-ray sources as 52.9%. We have also combined IRAS PSC and FSC catalogs and compiled its extragalactic sample, which allowed us to estimate AGN content among IR sources as 23.7%. Multiwavelength approach allowed revealing many new AGN and SB and obtaining a number of interesting relations using their observational characteristics and physical properties.

Statistical studies of active galaxies (both AGN and Starburst) using large multi-wavelength data are presented, including new studies of Markarian galaxies, large sample of IR galaxies, variable radio sources, and large homogeneous sample of X-ray selected AGN. Markarian survey (the First Byurakan Survey) was digitized and the DFBS database was created, as the biggest spectroscopic database by the number of objects involved ( ~ 20 million). This database provides both 2D images and 1D spectra. We have carried out a number of projects aimed at revealing and multi-wavelength studies of active galaxies among optical, X-ray, IR and radio sources. Thousands of X-ray sources were identified from ROSAT, including many AGN (52% among all identified sources). IRAS PSC/FSC sources were studied having accurate positions from WISE and a large extragalactic sample was created for further search for AGNs. The fraction of active galaxies among IR-selected galaxies was estimated as 24%. Variable radio sources at 1.4 GHz were revealed by cross-correlation of NVSS and FIRST catalogues using the method introduced by us for optical variability. Radio-X-ray sources were revealed from NVSS and ROSAT for detection of new active galaxies. Big Data in astronomy is described that provide new possibilities for statistical research of active galaxies and other objects.

Results of comparison of Gaia DR2 parallaxes with data derived from a combined analysis of 2MASS (Two Micron All-Sky Survey), SDSS (Sloan Digital Sky Survey), GALEX (Galaxy Evolution Explorer), and UKIDSS (UKIRT Infrared Deep Sky Survey) surveys in four selected high-latitude | b | &gt, 48&deg, sky areas are presented. It is shown that multicolor photometric data from large modern surveys can be used for parameterization of stars closer than 4400 pc and brighter than g S D S S = 19 . m 6 , including estimation of parallax and interstellar extinction value. However, the stellar luminosity class should be properly determined.

Optical identifications of a few thousands of IRAS sources showed that IRAS Point Source and IRAS Faint Source catalogues (PSC and FSC, respectively) contain many quasars and active galactic nuclei, late-type stars, planetary nebulae, variables, etc. To increase the efficiency of using IRAS PSC and FSC, which contain a lot of common sources, one needs a joint catalogue of all IRAS point sources with improved data based on both catalogues. However, cross-correlation of the catalogues is not so easy, as the association of many sources is relative, and not always it is obvious, whose source from one catalogue corresponds to the other one in the second catalogue. This problem exists in case of using standard cross-correlation tools like VizieR. Therefore, we have created a tool for cross-matching astronomical catalogues and we have applied it to IRAS PSC and FSC. Using this tool we have carried out identifications with a search radius corresponding to 3 σ of errors for each source individually rather than a standard radius for all sources. As a result, we obtained 73,770 associations. We showed that in case of cross-correlation of these catalogues by VizieR, we had to take 161.95 arcseconds radius not to lose any association; however, in this case a lot of false associations appear for many sources. In addition, we have made cross-correlations with AKARI-IRC, AKARI-FIS and WISE catalogues. As a result we created a catalogue with high positional accuracy and with 17 photometric measurements from 1.25 to 160 μm range, providing a detailed catalogue for IRAS point sources.

Byurakan Astrophysical Observatory (BAO), Byurakan 0213, Aragatzotn province, ArmeniaReceived 2013, accepted 2013Published online 2013Key words Markarian galaxies – multiwavelength studies – virtual observatoriesMarkarian galaxies are the result of the First Byurakan Survey (FBS) conducted in 1965-1980 by B.E. Markarian et al.The sample consists of 1515 UV-excess galaxies containing many active galaxies, both AGN and starburst (SB) that areinteresting from the point of view of galaxy evolution and multiwavelength studies. Several catalogs of Markarian galaxieshave been published; however multiwavelength (MW) data were not provided and matched for more efficient investiga-tions. Moreover, SDSS spectra now give possibility for better classification by activity types, and we have accomplishedfine classification obtaining new types and subtypes for most of the objects. We have cross-correlated Markarian cataloguewith all available large-area MW catalogues at various wavelengths, from X-ray to radio: ROSAT BSC and FSC, GALEX,APM, MAPS, USNO B1.0, GSC 2.3.2, SDSS, 2MASS PSC and ESC, WISE, AKARI-IRC, IRAS PSC, FSC, and SSSC,AKARI-FIS, GB6, NVSS, FIRST, SUMSS, WENSS, and 7C providing 35 photometric data-points, as well as the Dig-itized FBS (DFBS, http://byurakan.phys.uniroma1.it/) and Hamburg Quasar Survey (HQS) low-dispersion spectra. TheArmenian Virtual Observatory (ArVO, http://www.aras.am/Arvo/arvo.htm) services have been used for cross-correlationsand extraction of DFBS spectra, as well as MW SEDs have been built using the IVOA tools and MW classification hasbeen accomplished. Diagrams with MW flux ratios have been built to reveal objects with extreme characteristics. Theclassifications have been matched with these flux ratios. A MW catalog of Markarian galaxies has been compiled.

There have been 15 lists of late-type stars published between 1990 and 2010. These late-type stars have been found in the low-dispersion spectroscopic plates of the First Byurakan Survey (FBS). The systematic search and selection was carried out on a surface ∼16 000 deg2 on almost the whole area of the FBS. As a result, a comprehensive catalogue of the late-type stars of the FBS was generated. Its preliminary version has been available at the Centre de Donnes Astronomiques de Strasbourg since 2007. We have revised and updated the FBS catalogue of late-type stars with new data from recently published optical and multiwavelength catalogues to give access to all available data and to make further comparative studies of the properties of these objects possible. We have made cross-correlations with the Digitized First Byurakan Survey (DFBS), the United States Naval Observatory-B1.0 catalogue, the Guide Star Catalogue 2.3.2, Tycho-2, Sloan Digital Sky Survey Data Release 8, the Two-Micron All-Sky Survey (2MASS), the Wide-field Infrared Survey Explorer catalogue, the Infrared Astronomical Satellite Point Source Catalogue/Faint Source Catalogue, the AKARI catalogue, the ROSAT Bright Source Catalogue/Faint Source Catalogue, the General Catalogue of Variable Stars and the Northern Sky Variability Survey. Also, we have added updated SIMBAD data for the objects. We present accurate Digitized Sky Survey 2 positions, approximate spectral subtypes refined from the DFBS low-dispersion spectra, luminosity classes estimated from 2MASS colours and available proper motions for 1045 FBS late-type stars. The FBS revised and updated catalogue lists a large number of completely new objects, which promise to extend very significantly the census of M giants, faint carbon stars at high Galactic latitudes and M dwarfs in the vicinity of the Sun. We study the complete samples, as well as investigating individual interesting objects up to 16.0–16.5 mag in visual magnitudes.

A new method for the combined calculation of magnitudes based on accurate measurements of Palomar Observatory Sky Survey (POSS) epochs 1 and 2 (POSS 1 and POSS2) plates is given. The photometric accuracy of various surveys and catalogues has been estimated and established and statistical weights have been calculated for each one. To achieve the best possible magnitudes, weighted averaging of data from United States Naval Observatory (USNO-A2.0), Automatic Plate Measuring (APM), Minnesota Automated Plate Scanner (MAPS), USNO-B1.0 and Guide Star Catalog (GSC 2.3.2) catalogues has been used. The root-mean-square (rms) accuracy of magnitudes achieved for POSS1 is 0.184 mag for B and 0.173 mag for R, while that for POSS2 is 0.138 mag for B and 0.128 mag for R. We have derived the best POSS 1 and POSS2 magnitudes for First Byurakan Survey (FBS) blue stellar objects. We have refined the transformation formulae between POSS1 and POSS2 magnitudes and those for the Sloan Digital Sky Survey (SDSS) and a standard UBV system. Using these accurate magnitudes, we have estimated the variability of FBS blue stellar objects and revealed probable and possible variables. We have worked out methods with which to control and exclude the accidental errors that appear in any survey. We have compared and combined our results with those given in the Northern Sky Variability Survey (NSVS) data base and obtained better candidates for variability. Having excluded variables, we have combined POSS1 and POSS2 data for the remaining objects to achieve even better magnitudes and colours, the rms being smaller than 0.1 mag in both B and R and for B ― R colours. This approach has been applied to FBS blue stellar objects containing a significant number of white dwarfs (WDs) or cataclysmic variables (CVs), as well as extragalactic objects (quasars, Seyferts, BL Lac objects). Altogether 336 variable objects have been revealed, with POSS2―POSS1 ≥ 3σ of the errors. An electronic table of these objects is given. Candidate variables are divided into four classes: extreme, strong, probable and possible. For a more reliable sample of variable objects we excluded possible variables from the list and were left with 161 objects. By analysing the radio and X-ray properties of these objects we have revealed their nature and rediscovered or revealed candidate active galactic nuclei (AGNs), CVs, WDs and other objects.

A new method for combined calculations of proper motions (PMs) based on accurate measurements of POSS1 and POSS2 epoch plates is given. The positional accuracy of various surveys and catalogues is estimated, and statistical weights for each of them are established. To achieve the best positions, weighted averaging of direct measurements on DSS1/DSS2, and data from APM, MAPS, USNO-A2.0, USNO-B 1.0 and GSC 2.3.2 catalogues were used. The rms accuracy of positions achieved for POSS1 is 119 mas in each coordinate and 168 mas total, and for POSS2 it is 69 mas in each coordinate and 98 mas total. Using these accurate positions and the large separation in years between POSS1 and POSS2, we calculated the best possible PMs: 3.9 mas yr -1 in each coordinate and 5.5 mas yr -1 total. We developed methods to control and exclude the accidental errors that appear in any survey. We compared and combined our PMs with those given in USNO-B 1.0, SDSS DR7 and Tycho-2 catalogues and obtained even better results: 3.0 mas yr -1 in each coordinate and 4.2 mas yr -1 total PM. This approach was applied to the First Byurakan Survey blue stellar objects, containing significant numbers of white dwarfs and subdwarfs. In total, 640 objects were revealed with PM ≥ 10 mas yr -1 , the detection limit for this method, and an electronic table of these objects is given. For more confident PMs, we adopt the limit 20 mas yr -1 (333 objects). Adopting a 50 km s -1 upper limit for tangential velocities, we calculated maximum distances and absolute magnitudes and estimated luminosity types for these objects, obtaining 185 probable white dwarfs (M > 8 mag), 69 possible white dwarfs (6 < M < 8 mag), and 42 candidate subdwarfs/white dwarfs (3 < M < 6 mag). Given that we rediscovered 141 genuine white dwarfs among the classified objects, the success rate for the discovery of white dwarfs is estimated as 83 per cent, and as 38 per cent for our probable and possible white dwarfs, respectively.

A list of comparatively faint late M and Carbon type stars detected on the Digitized First Byurakan Survey (DFBS) spectral plates in the zone with +45° ≤ δ ≤ +49° covering 684 deg2 is presented. Accurate DSS2 positions, USNO-B1.0 B and R magnitudes, 2MASS near-infrared J, H, and Ks photometry, IRAS PSC/FSC fluxes (when available), approximate spectral types, and luminosity class estimates are given for 72 objects. Nine of them are newly confirmed carbon stars and 63 are M-type stars. For seven Mira variables with known pulsation periods we determined distances of 2 ÷ 8 kpc using a period-luminosity relation. Distances of 17 ÷ 115 pc for five M dwarfs, classified on the base of detected proper motions, were estimated using a color-luminosity relation. The object FBS 0845+466 is classified as a candidate carbon dwarf with distance r ≈ 72 pc.

Optically bright Galactic stars (V < 13 mag) having fv(24 um) > 1 mJy are identified in Spitzer mid-infrared surveys within 8.2 square degrees for the Bootes field of the NOAO Deep Wide-Field Survey and within 5.5 square degrees for the First Look Survey (FLS). 128 stars are identified in Bootes and 140 in the FLS, and their photometry is given. (K-[24]) colors are determined using K magnitudes from the 2MASS survey for all stars in order to search for excess 24 um luminosity compared to that arising from the stellar photosphere. Of the combined sample of 268 stars, 141 are of spectral types F, G, or K, and 17 of these 141 stars have 24 um excesses with (K-[24]) > 0.2 mag. Using limits on absolute magnitude derived from proper motions, at least 8 of the FGK stars with excesses are main sequence stars, and estimates derived from the distribution of apparent magnitudes indicate that all 17 are main sequence stars. These estimates lead to the conclusion that between 9% and 17% of the main sequence FGK field stars in these samples have 24 um infrared excesses. This result is statistically similar to the fraction of stars with debris disks found among previous Spitzer targeted observations of much brighter, main sequence field stars., Accepted for publication in The Astronomical Journal

Eleven lists of blue stellar objects (BSOs) were published in Astrophysics in 1990-1996, found in the First Byurakan Survey (FBS) low-dispersion spectroscopic plates. The selection was carried out in the region with +33° > δ > +45° and δ > +61° with a surface of 4000 deg2. As a result, the catalogue of the FBS BSOs was compiled. Its preliminary version has been available at Centre de Donnees Astronomiques de Strasbourg since 1999. We revised and updated the FBS BSOs catalogue with new data from recently published optical and multiwavelength catalogs to give access to all available data and make further comparative studies of the properties of these objects possible. We made cross-correlations of the FBS BSOs catalogue with the Minnesota Automated Plate Scanner, USNO-B1.0, Sloan Digital Sky Survey, and Two Micron All Sky Survey, as well as ROSAT, IRAS, NRAO VLA Sky Survey1The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc., and Faint Images of the Radio Sky at Twenty cm catalogs, added updated SIMBAD and NED data for the objects, and provided accurate DSS1 and DSS2 positions and revised photometry. We also checked the objects for proper motion and variability. A refined classification for the low-dispersion spectra in the Digitized First Byurakan Survey was carried out. The revised and updated catalogue of 1101 FBS BSOs is presented. The FBS BSOs catalogue can be used to study a complete sample of white dwarfs, hot subdwarfs, HBB stars, cataclysmic variables, bright active galactic nuclei, and to investigate individual interesting objects.

Context. Five lists of late-type stars were published in Astrophysics in 1997–2001, found in the First Byurakan Survey low-dispersion spectroscopic plates as optical identifications of unidentified IRAS sources. These identifications were carried out in the region with δ> +61 ◦ and |b| > 15 ◦ with a surface of 1504 deg 2 . As a result, the catalogue of the Byurakan-IRAS Stars (BIS) was compiled. Its preliminary version has been available at the CDS since 2003. Aims. We revised and updated the BIS catalogue with the new data from recently published optical and infrared catalogues to give access to all available data and make further comparative studies of the properties of these objects possible. Methods. We made cross-correlations of the BIS catalogue with the MAPS, USNO-B1.0, and 2MASS, added updated SIMBAD data for the BIS objects, and provided accurate DSS1 and DSS2 positions and revised photometry. We also checked the objects for proper motion and variability. A refined classification from low-dispersion spectra in the Digitized First Byurakan Survey (DFBS) was carried out. Results. The revised and updated catalogue of 276 Byurakan-IRAS stars (BIS) is presented. Conclusions. The BIS catalogue can be used to study a complete sample of IRAS-selected stars and to investigate individual objects.

The Byurakan/Hamburg/ROSAT Catalogue (BHRC) of the optical identifications of X-ray sources is presented. The BHRC includes all 2791 sources from the ROSAT-FSC with $|b|\ge30\degr$, $\delta\ge0\degr$ and ROSAT count rate $CR>0.04$ cts s -1 . For the optical identifications, we used the Hamburg Quasar Survey (HQS) digitized spectroscopic plates, the DSS1 and DSS2 (blue, red, and IR) images, the MAPS photometric data, the USNO-B1.0 (for proper motions), the NVSS and FIRST radio, and the IRAS and 2MASS infrared catalogues. From the DSS images we obtained positional, brightness, color, extension, variability, proper motion information, and measured the optical-to-X-ray distance. Based on the DSS images, a morphological classification was made. Available SIMBAD and NED data were used as well. Cross-correlations were made with AGN, white dwarf, and cataclysmic variable catalogues (322/8/7 associations, respectively). We managed to identify 97% of sources (2696 sources) that are associated with 3202 optical objects. 2248 X-ray sources have a single optical counterpart, 144 have a double or multiple optical counterpart (binaries, galaxy groups etc.), and 304 have ambiguous identifications. We find that some of the latest might actually be blends of two X-ray sources that were not resolved by ROSAT. The QSOs and AGN represent the largest group of X-ray counterparts (56.2%); bright stars (including late type stars, but excluding WDs and CVs) are counterparts for 33.2% of sources, and the bright galaxies and groups of galaxies comprise 9.2%. We found a number of close galaxy pairs (possibly interacting/merging galaxies) that are counterparts for X-ray sources (3.0%), as well as 1.0% WDs and 0.4% CVs. The BHRC may be used for selection and for studies of samples of various classes of X-ray emitters.

An international collaboration on the multiwavelength search for and studies of active galaxies between the Byurakan Astrophysical Observatory (Armenia) and Observatoire de Haute-Provence (France) ...

Spectroscopic observations by the 2.6 m BAO telescope of IRAS galaxies identified on the basis of the First Byurakan Survey (BIG objects) are reported. Slit spectra were obtained for 16 objects, including components of 7 multiple systems and 2 individual galaxies. The red shifts were measured, and the radial velocities, distances, absolute stellar magnitudes, and infrared and far infrared luminosities were calculated. A diagnostic diagram has been constructed based on the intensity ratios of emission lines and the activity types of the objects have been determined. Two LINERs, five galaxies with composite spectra (Comp, one of which has Sy2 features) and seven HII regions were found. Two objects are ultraluminous IR galaxies (ULIG). It is shown that all the multiple systems are physical pairs or groups. The observed high IR luminosity confirms the view that ULIG/HLIGs may be associated with interactions of galaxies.

The First Byurakan Survey (FBS) is the largest spectral survey in the Northern sky. Its plates contain low-dispersion spectra for some 20,000,000 objects. The FBS spectra allow selection of objects by their color, broad emission or absorption lines, or SED; to discover, classify and investigate them. The FBS was conducted originally to search for UVX galaxies (1500 Markarian galaxies were discovered). Selection of blue stellar objects, red stars, and identification of IRAS sources have also been done by means of the FBS spectra. All these projects have been carried out by visual inspection of the plates. Digitization will give new possibilities to search for many new objects: new bright QSOs (mm), new Markarian (UVX) galaxies, BCDGs, optical counterparts of IR, radio, X-ray and other sources, late-type stars, planetary nebulae, emission-line stars, and white dwarfs; and to study star clusters and clusters of galaxies. The digitized FBS will be available via the Internet and on CDs. Software and an appropriate interface for working with the data will be provided.

The spectral energy distribution (SED) gives a complete picture of the radiation of space objects and may result in correct classifications compared to those based only on optical (or other local) spectra. This is especially crucial for active galaxies, both AGN and Starbursts (SB). For this, multiwavelength (MW) data are needed taken from available surveys and catalogs. We have cross-correlated the Catalogue of quasars and active galaxies with all-sky or large-area MW catalogues, such as X-ray ROSAT (BSC and FSC), UV GALEX (MIS and AIS), optical APM, MAPS, USNO-B1.0, GSC 2.3.2, and SDSS DR8, NIR 2MASS, MIR/FIR WISE, IRAS (PSC and FSC) and AKARI (IRC and FIS), radio GB6, NVSS, FIRST, and WENSS. We have established accurate positions and photometry for a few thousands of objects that appeared in the catalog with poor data, as well as achieved the best astrometric and photometric data for all objects. This allowed correct cross-correlations and establishing correct MW data for these objects. As a result, we obtained 34 photometric points from X-rays to radio and using VO tools built SEDs for some 10,000 bright objects. Some data from other surveys were also used, such as Chandra, XMM, Spitzer, etc. All objects were grouped into several forms of SED and were compared to the known optical classes given in the catalog (QSO, BLL, Sy1, Sy1.2–1.9, Sy2, LINER, SB, and HII). This allowed reveal obscured AGN, as well as find previously misclassified objects. A homogeneous classification for these objects was established. The first part of this project is presented; establishment of accurate positions and photometry and cross-correlations with MW catalogs.

A new sample of some 900 faint IRAS galaxies will be constructed after optical identifications of all IRAS point sources from PSC and FSC in an area with 1500 deg2 at high galactic latitudes. The identifications are being made on the basis of FBS low-dispersion spectra, DSS images and infrared colours. Some 320 IRAS sources have been identified and 180 galaxies have been found. Spectral observations of these objects revealed new AGN and luminous infrared galaxies.

Part three of optically identified point sources from the IRAS Point Source Catalog contains 113 objects. The identifications were based on the Digitized Sky Survey (DSS), the First Byurakan Survey, blue and red maps from the Palomar Sky Survey, and infrared fluxes at 12, 25, 60, and 100 μm in the region of +61° ≤ δ ≤ + 65° and 11h15m ≤ α ≤ 18h35m with an area of 200 sq. deg. Of the 119 sources in this region, 6 could not be identified owing to the absence of optical counterparts with the given coordinates. For the identified objects we determined their optical coordinates, their departures from the IR coordinates, and their stellar V magnitudes, color indices (CI), and preliminary types. The objects have optical magnitudes in the range of 8n–21m. Of the 113 objects, 31 turned out to be stars of spectral types K and M, 1 is a planetary nebula, 2 are candidates to be quasi- stellar objects, and 79 are galaxies. A list of the 48 nonstellar objects is given. The identified galaxies include Seyfert candidates, interacting pairs, galaxies with companions, superassociations, etc. The galaxies are in groups in many cases, and the IR emission may be due to heating of intergalactic matter within a group. Finder charts for these objects from the DSS are given.

The Byurakan-IRAS Galaxy (BIG) sample (1967 galaxies) is based on optical identifications of IRAS PSC sources at δ>+61° and |b| >15° (FBS area). A redshift survey for brighter objects (Bm) is being carried out with the Byurakan Observatory 2.6m, Special Observatory 6m, and Observatoire de Haute-Provence 1.93m telescopes. 213 objects have been observed, and redshifts in the range 0.008-0.173 have been measured. For this subsample, 15% of the objects are AGNs, and 15% are LIGs and ULIGs.

We introduce accurate magnitudes as combined calculations from catalogues based on accurate measurements of POSS1- and POSS2-epoch plates. The photometric accuracy of various catalogues was established, and statistical weights for each of them have been calculated. To achieve the best possible magnitudes, we used weighted averaging of data from APM, MAPS, USNO-A2.0, USNO-B1.0 (for POSS1-epoch), and USNO-B1.0 and GSC 2.3.2 (for POSS2-epoch) catalogues. The r.m.s. accuracy of magnitudes achieved for POSS1 is 0.184 in B and 0.173 mag in R, or 0.138 in B and 0.128 in R for POSS2. By adopting those new magnitudes we examined the First Byurakan Survey (FBS) of blue stellar objects for variability, and uncovered 336 probable and possible variables among 1103 objects with POSS2–POSS1 ≥ 3σ of the errors, including 161 highly probable variables. We have developed methods to control and exclude accidental errors for any survey. We compared and combined our results with those given in Northern Sky Variability Survey (NSVS) database, and obtained firm candidates for variability. By such an approach it will be possible to conduct investigations of variability for large numbers of objects.

We present spectroscopic results for all galaxies observed with the Spitzer Infrared Spectrograph (IRS) that also have total infrared fluxes f IR measured with the Infrared Astronomical Satellite (IRAS), also using AKARI photometry when available. Infrared luminosities and spectral energy distributions (SEDs) from 8 μm to 160 μm are compared to polycyclic aromatic hydrocarbon emission from starburst galaxies or mid-infrared dust continuum from active galactic nuclei (AGNs) at rest-frame wavelengths ~8 μm. A total of 301 spectra are analyzed for which IRS and IRAS include the same unresolved source, as measured by the ratio f ν(IRAS 25 μm)/f ν(IRS 25 μm). Sources have 0.004 < z < 0.34 and 42.5 < log L IR < 46.8 (erg s–1) and cover the full range of starburst galaxy and AGN classifications. Individual spectra are provided electronically, but averages and dispersions are presented. We find that log [L IR/νL ν(7.7 μm)] = 0.74 ± 0.18 in starbursts, log [L IR/νL ν(7.7 μm)] = 0.96 ± 0.26 in composite sources (starburst plus AGN), log [L IR/νL ν(7.9 μm)] = 0.80 ± 0.25 in AGNs with silicate absorption, and that log [L IR/νL ν(7.9 μm)] = 0.51 ± 0.21 in AGNs with silicate emission. L IR for the most luminous absorption and emission AGNs are similar and 2.5 times larger than for the most luminous starbursts. AGNs have systematically flatter SEDs than starbursts or composites, but their dispersion in SEDs overlaps starbursts. Sources with the strongest far-infrared luminosity from cool dust components are composite sources, indicating that these sources may contain the most obscured starbursts.

A new sample of 1178 faint IRAS galaxies (BIG) has been constructed by means of optical identification of IRAS point sources from PSC in the region +61° < δ < +90° at high galactic latitudes over an area of some 1500 deg2. Compact galaxies, interacting pairs and groups, ‘mergers', radio and X-ray sources are among the identified objects. Spectral observations have revealed new AGNs and luminous infrared galaxies. Study of the sample gives better understanding of star-formation, nuclear activity, interactions and connections between these phenomena.

Extragalactic sources from the IRAS Faint Source Catalog (FSC) which have the optically faintest magnitudes (E > 18) were selected by spatial coincidence with a source in the FIRST radio survey, and 28 of these sources have been observed with the Infrared Spectrograph on Spitzer (IRS). While an infrared source is always detected with the IRS at the FIRST position, only ~ 50% of the infrared sources are real FSC detections, as estimated from the number of sources for which the fv(25um) determined with the IRS is fainter than the sensitivity limit for the FSC. Sources have 0.12 < z < 1.0 and luminosities (ergs per s) 43.3 < log[vLv(5.5um)] < 46.7, encompassing the range from local ULIRGs to the most luminous sources discovered by Spitzer at z ~ 2. Detectable PAH features are found in 15 of the sources (54%), and measurable silicate absorption is found in 19 sources (68%); both PAH emission and silicate absorption are present in 11 sources. PAH luminosities are used to determine the starburst fraction of bolometric luminosity, and model predictions for a dusty torus are used to determine the AGN fraction of luminosity in all sources based on log[vLv(5.5um)]. Approximately half of the sources have luminosity dominated by an AGN and approximately half by a starburst. The ratio of infrared to radio flux, defined as q = log[fv(25um)/fv(1.4 GHz)], does not distinguish between AGN and starburst for these sources., Accepted for publication in The Astrophysical Journal

Context. The First Byurakan Survey (FBS), also known as the Markarian Survey, is the largest low resolution spectroscopic survey of the sky and led to the discovery of 1500 UV-excess (UVX) galaxies and starburst galaxies. The FBS plates have also been used to search for UVX stellar objects, late-type stars, and for the identification of unusual infrared sources.Aims. The Digitized First Byurakan Survey (DFBS) provides the astronomical community with a digitized version of the FBS images and with the extracted spectra for the objects present in the plates.Methods. Nearly 2000 plates have been scanned and stored and programs were developed to compute the astrometric solution, extract the spectra, and apply wavelength and photometric calibration for the objects present in the plates.Results. The DFBS database and catalog of objects has been assembled. The DFBS database contains data for 20 000 000 objects present in the survey and provides tools for accessing the DFBS.Conclusions. New scientific projects as well as existing surveys will benefit by the digitized images and the ready-to-use extracted spectra which will allow an efficient computer-based analysis of the dataset.

The combined catalogue of AGN selected from optical identifications of X-ray sources based on Hamburg–ROSAT and Byurakan–Hamburg–ROSAT catalogues is a homogeneous sample for statistical studies. Optically identified X-ray sources from ROSAT BSC and FSC are included, 4253 X-ray selected AGN in total. We carried out classification for 210 of these candidate sources based on available SDSS spectra and enlarged the sample of confirmed AGN. Statistical investigations of the sample were also carried out. Multiwavelength SEDs have also been constructed to link them to classifications.

High–redshift quasars and blazars are among the most powerful sources in the Universe and among the highest luminosity sources, as in optical, so as in X–ray, UV, IR and radio range. We have created a full sample of blazars and high–redshift quasars (z≥2.15). The evolutionary relation of high–redshift quasars and blazars to high–redshift galaxies is discussed using the luminosity evolution.

A summary and general analysis of optical spectroscopic data for 255 Byurakan-IRAS Galaxies (BIG) obtained with BAO 2.6m, SAO 6m, OHP 1.93m telescopes, as well as SDSS DR7, DR8, and DR9 is given. The BIG sample is the result of optical identifications of IRAS PSC sources at high-galactic latitudes using the First Byurakan Survey (FBS) low-dispersion spectra. Among the 1178 objects most are spiral galaxies and there is a number of ULIRGs. All but one have emission lines; we have discovered 68 AGN and composite spectrum objects among them and the others are mostly Starburst Galaxies (SB). All possible physical characteristics have been measured and/or calculated, including physical sizes and optical and IR/FIR luminosities. The masses have been estimated based on mass-luminosity relations for spiral galaxies. As it appears, most of these objects are giant massive galaxies. Various multiwavelength (MW) data have been retrieved from recent catalogues from X-ray to radio and MW SEDs have been built, which have been matched to their optical classifications. Luminosity evolution of these objects has been studies.

Byurakan Astrophysical Observatory (BAO), Byurakan 0213, Aragatzotn province, ArmeniaEmail: gurgen@bao.sci.am, abrahamyanhayk@gmail.com, goharutyunyan@gmail.com,aregmick@aras.amAbstract. We attempt to create an X-ray/radio AGN catalog and make its multiwavelengthstudies. ROSAT Bright Source Catalogue (BSC) contains 18,806 and ROSAT Faint Source Cat-alogue (FSC), 105,922 X-ray sources giving the total number of ROSAT X-ray sources 124,727(one source is listed twice). On the other hand, NVSS radio catalogue contains 1,773,484 sources.Taking into account that X-ray sources contain AGN, bright stars and galaxies, clusters, whitedwarfs (WD), cataclysmic variables (CV), etc., the cross-identification with radio catalogue maydistinguish the extragalactic sources. We have cross-correlated ROSAT catalogs with NVSS onewith a search radius 30 arcsec. 9,193 associations have been found. To distinguish AGN fromthe normal bright galaxies and clusters, Veron-Cetty & Veron AGN catalog (v.13, 2010; VCV-13) containing 168,940 objects have been used. A cross-correlation of the 9,193 ROSAT/NVSSsources with the VCV-13 with a search radius 30 arcsec resulted in 3,094 associations. Thus weare left with more 6,099 X-ray/radio sources without an optical identification. Brighter objectsare normal bright galaxies, while we believe that all faint ones are candidate AGN with somecontamination of distant clusters. SDSS spectroscopic survey allows us classify objects by ac-tivity types, and a number of our candidate AGN is found to be present in SDSS. We attemptto find connections between the fluxes in different wavelength ranges, which will allow us toconfirm AGN and blazars candidates and in some cases find new ones.Keywords. X-ray and radio surveys, SDSS, cross-correlations, AGN, AGN candidates

The sample of Markarian galaxies consists of 1515 UV-excess galaxies containing many active galaxies, both AGN and Starburst (SB). Several catalogs of Markarian galaxies have been published; however activity types are based on old spectroscopic data. The SDSS spectroscopy and some other recent spectral observations allow classify or re-classify many of Markarian galaxies, altogether we have retrieved and studied 779 SDSS and 300 other spectra. Out of 779 SDSS spectra, we have classified 533 HII, 31 Composites, 12 LINERs, 4 S2.0, 5 S1.9, 8 S1.8, 5 NLS1.5, 11 S1.5, 8 NLS1.2, 21 S1.2, 4 NLS1, 4 S1.0, 2 QSO, 11 AGN (without an exact class), 52 Em (HII or AGN), 65 Abs, and 3 Stars. On the other hand, the galaxies are being classified depending on the fact in which wavelength range they have been observed and studied. E.g. some Sy2 type galaxies turn to be Sy1 when classified in IR. Many hidden AGN (in X-ray and IR) appear to be normal galaxies in optical range. So for better understanding, IR spectra are necessary as well.

The Byurakan-IRAS Galaxy (BIG) sample is the result of optical identifications of IRAS PSC sources at high-galactic latitudes using the First Byurakan Survey (FBS) low-dispersion spectra. Among the 1178 objects most are spiral galaxies and many have been proved to be AGN and starburst by spectroscopic observations, as well as there is a number of ULIRGs among these objects. BIG objects contain galaxy pairs, multiples, and small groups that are subject for study on the matter of the real IR-emitter in these systems. Given that these objects are powerful IR sources, they are considered as young systems indicating high rate of evolution and starburst activity exceeding 100 Mo/yr. Spectroscopic observations show that all these systems are physical ones and we were able to measure the mutual distances and sizes for all components. Cross-correlations with the recent more accurate IR catalogues, such as 2MASS and WISE, as well as radio ones (NVSS, FIRST), provided accurate coordinates of the IR source and possibility to find the individual galaxy responsible for the IR. However, in almost half of the cases, IR position indicates the intermediate region between the components, which means that it comes from the system as a whole. Some more MW data have been matched to IR and radio to have an overall understanding on these systems. Given that these systems are mostly interacting/merging ones often containing AGN and most of them may be considered as powerful starbursts, it is possible to study starburst/activity/interaction phenomena and their interrelationship.

The Joint Catalogue of Hamburg ROSAT Sources (HRC/BHRC) is the result of merging of HRC and BHRC catalogs built on the basis of optical identifications of ROSAT BSC and ROSAT FSC. Altogether, 8132 sources are present. Based on this catalogue, we have compiled a sample of ROSAT AGN, including candidate ones. In this paper we classify candidate AGN (those that previously had not been spectroscopically classified) by their activity type. The sample contains 955 objects with count rate of photons CR>0.04 ct/s in the area with galactic latitudes |b|>30 and declinations δ>0, however only 217 objects have SDSS DR10 spectra. The classification led to the following results: 95 AGN, 71 absorption-line galaxies, 42 stars, and 9 unclassified objects.

Optical identification of infrared sources from the IRAS Point Source Catalogue (PSC) is made by means of low-dispersion spectra of the First Byurakan Survey (FBS) and Palomar Observatory Sky Survey (POSS) red and blue images. The purpose of this work is to examine the composition of the PSC sample of fainter sources at high galactic latitudes and to reveal QSOs, infrared galaxies, red stars (C and M), planetary nebulae, for their further investigation at the optical range. 100 of 108 unknown IRAS sources in the region with 3h50m ≤α ≤ 7h40m and + 69° ≤δ ≤ + 73° are optically identified. Optical coordinates, V magnitudes, color indices, and preliminary classes are determined. According to preliminary classification 3 objects turned out to be QSOs, 36 are galaxies with very interesting morphology, 5 are faint planetary nebulae, 9 are carbon stars, and 47 are late M-type stars.

To build a large, optically bright, X-ray selected AGN sample we have correlated the ROSAT-FSC catalogue of X-ray sources with the USNO catalogue limited to objects brighter than O=16.5 and then with the APS database. Each of the 3,212 coincidences was classified using the slitless Hamburg spectra. 493 objects were found to be extended and 2,719 starlike. Using both the extended objects and the galaxies known from published catalogues we built up a sample of 185 galaxies with O_APS < 17.0 mag, which are high-probability counterparts of RASS-FSC X-ray sources. 130 galaxies have a redshift from the literature and for another 34 we obtained new spectra. The fraction of Seyfert galaxies in this sample is 20 %. To select a corresponding sample of 144 high-probability counterparts among the starlike sources we searched for very blue objects in an APS-based color-magnitude diagram. Forty-one were already known AGN and for another 91 objects we obtained new spectra, yielding 42 new AGN, increasing their number in the sample to 83. This confirms that surveys of bright QSOs are still significantly incomplete. On the other hand we find that, at a flux limit of 0.02 count /-1 and at this magnitude, only 40 % of all QSOs are detected by ROSAT., 17 pages, 16 figures, accepted by A&A

We report the discovery of a new bright (V$\sim$12.6) cataclysmic variable star identified with the ROSAT X-ray source RX J1643.7+3402. Spectroscopic and photometric observations show it to be a novalike variable sharing some of the characteristics of the SW Sex sub-class of novalike CVs. The spectroscopic period may be either 2\fh575 or 2\fh885, within the period "gap." A photometric modulation with a probable period of 2\fh595 and an amplitude of $\sim$ 0.1 mag in V is present on most nights and could be either a "positive" or a "negative" superhump modulation (depending on the exact spectroscopic period), indicating the presence of a precessing accretion disk in this system. Rapid variations of 0.1 to 0.2 mag amplitude in V repeat with a time scale of $\sim$ 15 min., Comment: 11 pages, 12 figures, accepted in Astronomy & Astrophysics

International audience; Faint high-latitude carbon stars (FHLCs) are distant, luminous giants. For this reason, they are often used to study the dynamical and chemical properties of the Galactic Halo. However, a more accurate investigation of photometric and spectroscopic surveys has revealed an increasing number of such objects with luminosities of main sequence stars. We report the first results of a systematic search of FHLCs using the Digitized First Byurakan Survey (DFBS) low-resolution spectral database. The DFBS low-resolution spectral plates are analysed to find new faint early and late-type carbon star candidates. Twenty new faint high-latitude carbon star candidates have been detected in an area of ∼4030 sq. deg. Moderate-resolution slit spectroscopy was carried out for all candidates, confirming the carbon star nature for thirteen of them (nine are new discoveries), while the remaining objects are M-type stars. The carbon star sample consists of five N-type carbon stars, for which the estimated mass-loss rates agree well with the typical ones found for such carbon stars; five comparatively bright CH-type carbon stars; and three are probably dwarf carbon (dC) stars. The distance determination indicates that the dwarf carbon stars belong to the thin disk, while the other stars belong the Galactic halo. These results demonstrate that one can efficiently find new faint high-latitude carbon star in the Digitized First Byurakan Survey database.

The Byurakan-IRAS Galaxy (BIG) sample (Mickaelian 1995) is the result of optical identifications of IRAS PSC sources at high-galactic latitudes using the First Byurakan Survey (FBS) low-dispersion spectra (Markarian et al. 1989). Among the 1577 objects 1178 galaxies have been identified. Most are dusty spiral galaxies and there are a number of ULIRGs among these objects. Our spectroscopic observations carried out with three telescopes (Byurakan Astrophysical Observatory 2.6m, Russian Special Astrophysical Observatory 6m and Observatoire de Haute Provence 1.93m) (Mickaelian & Sargsyan 2010) for 172 galaxies, as well as the SDSS DR8 spectra for 83 galaxies make up the list of 255 spectroscopically studied BIG objects. The classification to activity types for narrow-line emission galaxies has been carried out using the diagnostic diagrams by Veilleux & Osterbrock (1987). All possible physical characteristics have been measured and/or calculated, including radial velocities and distances, angular and physical sizes, absolute magnitudes and luminosities (both optical and IR). IR luminosities and star-formation rates have been calculated from the IR fluxes (Duc et al. 1997).Among the 172 observed galaxies, 102 starburst (HII) ones, 29 AGN (Sy or LINER), and 19 galaxies with composite spectrum have been revealed; spectra of 12 galaxies show emission features but without a possibility for more accurate classification, 9 galaxies are presented as galaxies where the star formation rate does not exceed normal one, and 1 galaxy is an absorption galaxy. Among the 83 objects having SDSS spectra, there are 55 HIIs, 8 Seyferts, 2 LINERs, 4 other AGN (without accurate classification), 6 composite spectrum objects and 8 other emission-line galaxies. In our spectroscopic sample we have 43 (17%) AGN, 25 (10%) composite spectrum objects, 157 (62%) starbursts, 29 emission-line galaxies without a definite type, and 1 absorption-line galaxy. There are 3 Ultra-Luminous InfraRed Galaxies (ULIRG).Various multiwavelength (MW) data have been retrieved for the full sample of 1178 objects from recent catalogs from X-ray to radio (ROSAT, GALEX, APM, MAPS, USNO, GSC, SDSS, 2MASS, WISE, IRAS, AKARI, NVSS, FIRST, etc.) to make a complete study of these galaxies possible. MW SEDs have been built, which have been matched to their optical classifications. Star-formation rates have been calculated to compare to their other physical characteristics, such as morphology, activity types, UV, optical, IR and radio luminosities, etc.

The Second part of the FBS is devoted to the discovery and study of blue stellar objects. It was carried out in an area of 4009 deg2 and identified 1103 objects: hot subdwarfs and white dwarfs, cataclysmic variables, QSOs and Seyfert galaxies, etc. The discovery of new bright QSOs led to a re-evaluation of their surface density (0.012 deg−2). Several interesting cataclysmic variables have been discovered as well.

We have discovered a number of sources still remaining in the IRAS catalogs with no convincing optical identification. Their IR colors and high galactic latitudes indicate faint galaxies (fainter the DSS limit). These empty fields have been observed with the Byurakan Obs. 2.6m telescope in VRI. 22m–23m faint formations have been revealed.

Numerous new Solar System objects, mainly asteroids, are still detected nowadays but their physical and dynamical characteristics remain not accurately determined, until dedicated observations and analysis are made. However, the Virtual Observatory is a perfect framework to search for this characterization by data mining. We are developing two studies for this goal by exploring the DENIS infrared and DFBS spectroscopic surveys. In order to scan the survey catalogues and to search for Solar System objects, we have developed a VO compliant workflow founded on the use of a recent VO tool labelled SkyBoT (Sky Bodies Tracker) (Berthier et al. 2005) and on the VizieR service provided by CDS. A public version of SkyBoT is implemented in the sky atlas Aladin since January 2006. It allows us to quickly get the precise coordinates of the asteroids, planets and natural satellites in any star field, provided we know its center, its size and the precise date of the exposure (between 1949 and 2009). Our data mining workflow performs cone search queries on SkyBoT and VizieR to extract all the known astronomical objects observed by the survey. Then the sources which are detected in the survey are correlated with the known objects to determine the matched and unmatched objects.

The main goal of the Armenian Virtual Observatory is to develop efficient methods for science projects based on the digitized famous Markarian survey (Digitized First Byurakan Survey, DFBS) and other large astronomical databases, both Armenian and international. Two groups of projects are especially productive: search for new interesting objects of definite types by low-dispersion template spectra, and optical identifications of new gamma, X-ray, IR and radio sources. The first one is based on modeling of spectra for a number of types of objects: QSOs, Seyfert galaxies, white dwarfs, subdwarfs, cataclysmic variables, planetary nebulae, late-type stars (K-M, S, carbon), etc. Each kind of object appears in the DFBS with its typical SED and spectral lines (for objects having broad lines only, like white dwarfs and subdwarfs, quasars and Seyferts, etc.), however affected also by its brightness, so that each template works for definite range of magnitudes. The search criteria define how many objects will be found for further study, and may restrict these numbers leaving with the best candidates. Optical identifications have been proven to be rather efficient for IR sources from IRAS-psc and -fsc. Tests have been carried out for X-ray and radio sources as well. Special emphasis is put on search for bright QSOs missed by the Sloan Digital Sky Survey (SDSS), rather important for making up their complete sample, studies of the properties of the Local Universe, a comparison of their X-ray, IR, and radio properties and making up their multiwavelength SEDs, as well as for a refinement of the AGN classification. A project for search for new bright QSOs using the DFBS has been started in the region with δ>0° and |b|>20°. The Byurakan 2.6m telescope is being used for the spectral identification of the candidates. The first test resulted in 145 objects found, 81 being known QSOs/Sys, and 64 new candidates (including 23 NVSS and FIRST radio sources).