URL: https://www.sciencedirect.com/science/article/pii/S2213133714000699

DOI: https://doi.org/10.1016/j.ascom.2014.12.002

Նկարագրություն: 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.

URL: https://www.sciencedirect.com/science/article/pii/S2213133717300896?via%3Dihub=

DOI: https://doi.org/10.1016/j.ascom.2018.09.012

Նկարագրություն: 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.

URL: https://onlinelibrary.wiley.com/doi/abs/10.1002/asna.201913603

DOI: https://doi.org/10.1002/asna.201913603

Նկարագրություն: The analysis of blazars' parameters from BZCAT leads to a conclusion that they
do not have the same properties. The preliminary criterion to include an object in
the catalog was the strong radio emission; however, two type of radio sources were
selected: BL Lacertae (BLL) objects and Flat Spectrum Radio Quasars (FSRQ). As a
number of properties are typical of blazars (strong radio emission, optical variability,
continuum optical spectra, polarization, high luminosity, etc.), using the optical data,
we investigate them to clarify which property plays the most significant role in their
classification as blazars. We found that 60% of blazars have optical variability. We
use a technique developed based on POSS1 and POSS2 photometry and group the
variability into extreme, strong, medium, and low classes. In the optical range, 51
blazars have powerful variability (extreme variables), and 126 are high variables.
In addition, 63% of blazars have detected radiation in X-ray and 28% have detected
radiation in gamma rays. We give the average statistical characteristics of blazars
based on our analysis and calculations.

DOI: https://doi.org/10.1002/asna.202013701

Նկարագրություն: In this paper, we investigate radio properties of active galaxies taken from the reference [Véron‐Cetty & Véron (2010)] catalog. The galaxies are limited to magnitudes in the range of 12m  − 19m . We have cross‐correlated the list with radio catalogs and selected those galaxies that have data on six or more radio fluxes at different wavelengths. As a result, we have 198 galaxies that satisfy these conditions. Using SDSS DR15, we have obtained 96 spectroscopic identifications of the 198 objects. After the classification, 85% of the 96 objects have changed their types. Available data on the classification of these objects and our classification showed that 56.7% of them are Seyfert galaxies. For all the objects, we have built radio spectra and estimated radio spectral indices. As a result, we obtain urn:x-wiley:00046337:media:asna202013701:asna202013701-math-0001, urn:x-wiley:00046337:media:asna202013701:asna202013701-math-0002, urn:x-wiley:00046337:media:asna202013701:asna202013701-math-0003, urn:x-wiley:00046337:media:asna202013701:asna202013701-math-0004). We discuss the radio properties of active galaxies based on their radio spectral indices.

URL: https://www.springer.com/journal/10511

Նկարագրություն: This work provides a detailed spectral classification of 96 active galaxies from the Véron-Cetty and Véron catalog (2010, 13th version, VCV-13), which is a catalog of active galaxies and quasars. These objects were identified as radio sources using different radio catalogs in different radio bands. Having data from radio catalogs, we took those galaxies that had radio streams in at least 6 different radio bands and optical spectral identification from the SDSS catalog. Using the spectra from the SDSS catalog, these 96 objects were studied and detailed types of activity for them. For a more confident classification wå used three diagnostic charts and a direct study of the spectra. As a result, we have changed classification for 85% of these objects. Radio radiation in different radio bands allows us to build the spectral energy distribution in the radio and compare with the optical types of activity.

URL: https://www.bao.am/specialcouncil/Abrahamyan/2.pdf