ROXA ivo://nasa.heasarc/roxa NASA/GSFC HEASARC Turriziani et al. 2026-04-24 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source Although blazars are a small fraction of the overall AGN population, they are expected to be the dominant population of extragalactic sources in the hard X-ray and gamma-ray bands and have been shown to be the largest contaminant of CMB fluctuation maps. So far the number of known blazars is of the order of several hundreds, but the forthcoming AGILE, GLAST and Planck space observatories will detect several thousand of objects of this type. In preparation for these missions it is necessary to identify new samples of blazars to study their multi-frequency characteristics and statistical properties. The authors have compiled a sample of objects with blazar-like properties via a cross-correlation between large radio (NVSS, ATCAPMN) and X-ray surveys (RASS) using the SDSS-DR4 and 2dF survey data to spectroscopically identify their candidates and test the validity of the selection method. They present the Radio-Optical-X-ray catalog built at ASDC (ROXA), a list of 816 objects among which 510 are confirmed blazars. Only 19% of the candidates turned out to be certainly non-blazars, demonstrating the high efficiency of our selection method. This catalog includes 173 new blazar identifications, or about 10% of all presently known blazars. The relatively high flux threshold in the X-ray energy band (given by the RASS survey) preferentially selects objects with high F_X/F_r ratio, leading to the discovery of new High Energy Peaked BL Lac (HBLs). This catalog therefore includes many new potential targets for GeV-TeV observations. The selection method consisted of three steps: 1) a first cross-correlation between radio and X-ray surveys (the NRAO VLA Sky Survey, ATCAPMN (ATCA catalogue of compact PMN sources) and ROSAT All Sky Survey; 2) for each radio/X-ray match, optical magnitudes were retrieved from the Guide Star Catalog; 3) for all radio/optical/X-ray matches the authors calculated the X-ray to optical (alpha_ox) and radio to optical (alpha_ro) spectral slopes and took only sources with alpha_ox and alpha_ro values within the blazar area. For each object, redshift, B and G magnitudes, radio fluxes at 1.4 GHz and at 5 GHz, X-ray flux, F_X/F_r ratio, X-ray luminosity, radio luminosity, Ca H&K break and classification are given. This table was created by the HEASARC in November 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/472/699">CDS catalog J/A+A/472/699</a> file catalog.dat. This is a service provided by NASA HEASARC . 2007A&A...472..699T https://heasarc.gsfc.nasa.gov/W3Browse/all/roxa.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=roxa& GET text/xml 180 99999 true 42.69333333 -34.81355556 0.0333333333333333 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=roxa GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_roxa&Action=More+Options&Action=Parameter+Search&ConeAdd=1 ROSAT 0.0333333333333333 X-ray Radio Optical public roxa ROXA (Radio-Optical-X-ray at ASDC) Blazars Catalog name Source Designation Based on Position (JHHMMSS.s+DDMMSS.s) meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable redshift Redshift src.redshift double nullable gmag g-prime Magnitude (from SDSS Survey) mag phot.mag;em.opt.B double nullable flux_20_cm Radio Flux at 1.4GHz (NVSS) (mJy) mJy phot.flux.density;em.radio.750-1500MHz double nullable flux X-Ray Flux (RASS) (erg/s/cm^2) erg/s/cm^2 phot.flux;em.X-ray.soft double nullable source_type Source Classification src.class char nullable lx X-Ray Luminosity (erg/s) erg/s phys.luminosity;em.X-ray.soft double nullable bj_mag Bj Magnitude (from 2dF Surveys) mag phot.mag;em.opt.B double nullable xray_radio_ratio Ratio between X-Ray Flux and Radio Flux erg/s/cm^2/Jy phot.flux;arith.ratio double nullable calcium_break Calcium Break spect;spect.continuum;arith.ratio double nullable source_flag Flag Indicates Note on Class meta.code char nullable class Browse Object Classification src.class short nullable flux_6_cm Radio Flux at 5GHz (North6cm, GB6 and PMN) (mJy) mJy phot.flux.density;em.radio.3-6GHz double nullable lii Galactic Longitude degree pos.galactic.lon double nullable bii Galactic Latitude degree pos.galactic.lat double nullable lradio Radio Luminosity (erg/s/Hz) erg/s/Hz phys.luminosity;em.radio double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable