This is the Hewitt & Burbidge (1991) Optical Catalog of Extragalactic Emission-Line Objects Similar to Quasi-Stellar Objects. It contains a total of 935 galaxies which have optical properties similar to QSOs. Most of the objects appear to be nonstellar. The majority, more than 700, have redshifts z that are <= 0.2, and most have been classified as Seyfert galaxies, N systems, or radio galaxies. The redshift distribution peaks at z ~ 0.025, but there are about 200 powerful radio galaxies in the extended tail of the distribution which have z > 0.2. There is a separate and distinct peak in the redshift distribution at z = 0.06. Notice that this catalog does not include star-like objects with emission-line redshifts >= 0.1 (these can be found in the HEASARC QSO database which contains the Revised and Updated Catalog of Quasi-Stellar Objects" of Hewitt, A. and Burbidge, G. 1993, ApJS, Vol. 87, pp. 451-947). Neither does it contain LINERs (sometimes called Seyfert 3 galaxies) or starburst galaxies. This database was created by the HEASARC in February 2001 based on CDS/ADC Catalog VII/178 (table1.dat). This is a service provided by NASA HEASARC .

The authors have compiled a catalog of optically selected quasars with simultaneous observations in UV/optical and X-ray bands by the Swift Gamma-ray Burst Explorer. Objects in this catalog are identified by matching the Swift pointings with the Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5) quasar catalog. The final catalog contains 843 objects, among which 637 have both Ultraviolet Optical Telescope (UVOT) and X-Ray Telescope (XRT) observations and 354 of which are detected by both instruments. The overall X-ray detection rate is ~ 60% which rises to ~ 85% among sources with at least 10 ks of XRT exposure time. The authors construct the time-averaged spectral energy distribution (SED) for each of the 354 quasars using UVOT photometric measurements and XRT spectra. From model fits to these SEDs, they find that the big blue bump contributes about ~ 0.3 dex to the quasar luminosity. The authors re-visit the alpha_ox - L_2500A relation by selecting a clean sample with only Type 1 radio-quiet quasars; the dispersion of this relation is reduced by at least 15% compared with studies that use non-simultaneous UV/optical and X-ray data. They find only a weak correlation between L_bol/L_Edd and alpha_UV. They do not find significant correlations between alpha_x and alpha_ox, alpha_ox and alpha_UV, and alpha_x and log L(0.3-10 keV). The correlations between alpha_UV and alpha_x, alpha_ox and alpha_x, alpha_ox and alpha_UV, L_bol/L_Edd and alpha_x, and L_bol/L_Edd and alpha_ox are stronger among low-redshift quasars, indicating that these correlations are likely driven by the changes of SED shape with accretion state. This quasar sample was compiled in the following steps: 1. Candidate objects for the catalog were selected as any SDSS DR5 quasar that lie within 20 arcminutes of the center of the Swift FOV in any pointing from launch through 2008 June. 2. XRT data were processed to obtain X-ray count rates, spectra, and spectral parameters. 3. UVOT data were processed to obtain UV and optical photometry. 4. UVOT photometry were supplemented with measurements at other wavelengths from published catalogs. 5. Quasar SEDs were constructed. 6. Additional parameters were calculated based on the SEDs of each quasar. The raw sample is constructed by matching 3.5 years Swift pointings and the SDSS DR5 quasar catalog and contains 1034 objects. This HEASARC version of this catalog contains all 1034 objects in the "raw" catalog. To select only the 843 objects in the "final" catalog, the user should specify catalog_flag = 1 in any searches of this table. This table was created by the HEASARC in August 2012 based on an electronic version of Table 8 from the reference paper which was obtained from the ApJS web site. This is a service provided by NASA HEASARC .

Positions, redshifts, and magnitudes for the 1055 quasars in the Large Bright Quasar Survey (LBQS) are presented in a single catalog. Celestial positions have been rederived using the PPM catalog to provide an improved reference frame. Redshifts calculated via cross correlation with a high signal-to-noise ratio composite quasar spectrum are included and the small number of typographic and redshift misidentifications in the discovery papers are corrected. Compared to the discovery papers (references below), 12 quasars that are either fainter than the field magnitude limit or fall outside the final survey area have been deleted, 12 quasars that were discovered subsequent to paper V have been added, 10 redshifts have been corrected, and 13 quasars with either incorrect or degenerate designations (LBQS names) have had their designations corrected. The information in this version of the LBQS Catalog is the same as in Table 4 of the published paper with the following exceptions: (i) the object 0021-0213 has a redshift of 2.348; this value was listed in Table 5 of the paper but was not incorporated in Table 4 of the paper; (ii) the parameter 'Reference' in Table 4 of the published paper (which specified in which paper in the LBQS series the quasar spectrum could be found) has been omitted; and (iii) the parameter 'Notes' in Table 4 of the published paper had two non-blank values: '+' and 'a'; in the HEASARC representation of this catalog we have replaced the Notes value of '+' by 'C', and dropped the Notes value of 'a' (used to indicate objects that had been listed as AGN in earlier papers). This catalog was created by the HEASARC in July 1999 based on a table that was kindly provided by the first author, Paul Hewett, supplemented by documentation created by the CDS/ADC. This is a service provided by NASA HEASARC .

This table contains a catalog of 312 X-ray selected BL Lacertae objects (XBLs), optically identified through the end of 2011. It contains the names from different surveys, equatorial coordinates, redshifts, multi-frequency flux values, and luminosities for each source. In the reference, the different characteristics of these XBLs are statistically investigated (redshift, radio/optical/X-ray luminosities, central black hole (BH) mass, synchrotron peak frequency, broadband spectral indices, optical flux variability). Their values were collected through an extensive bibliographic and database search or calculated by the author. The redshifts range from 0.031 to 0.702 with a maximum of the distribution at z = 0.223. The 1.4-GHz luminosities of XBLs log (nu * L_nu) ~ 39 - 42 (in units of erg s^-1), while the optical V and X-ray (0.1-2.4 keV) bands show log (nu * L_nu) ~ 43 - 46 (same units). The XBL hosts are elliptical galaxies with effective radii r_eff = 3.26 - 25.40 kpc and ellipticities e = 0.04 - 0.52. Their R-band absolute magnitudes M_R range from -21.11 mag to -24.86 mag with a mean value of -22.83 mag. The V - R indices of the hosts range from 0.61 to 1.52 and reveal a fourth-degree polynomial relationship with z that enabled the author to evaluate the redshifts of five sources whose V - R indices were determined from the observations, but whose redshifts values are either not found or not confirmed. The XBL nuclei show a wider range of 7.31 mag for M_R, with the highest luminosity corresponding to M_R = -27.24 mag. The masses of the central BHs are found in the interval log M_BH = 7.39 - 9.30 (in units of solar masses), with the maximum of the distribution at log M_BH/M_sun = 8.30. The synchrotron peak frequencies are spread over the range log nu_peak = 14.56 - 19.18 Hz, with a peak of the distribution at log nu_peak = 16.60 Hz. The broad-band radio-to-optical (alpha_ro), optical-to-X-ray (alpha_ox), and radio-to-X-ray (alpha_rx) spectral indices are distributed in the intervals (0.17, 0.59), (0.56, 1.48), and (0.41, 0.75), respectively. In the optical energy range, the overall flux variability increases, on average, towards shorter wavelengths: Delta(m) = 1.22, 1.50, and 1.82 through the R, V, B bands of the Johnson-Cousins system, respectively. XBLs seem be optically less variable at intranight timescales compared to radio-selected BL Lacs (RBLs). This table was created by the HEASARC in June 2013 based on an electronic version of Table 2 from the reference paper which was obtained form the AJ web site. This is a service provided by NASA HEASARC .