« Previous |
21 - 26 of 26
|
Next »
Number of results to display per page
Search Results
- ID:
- ivo://nasa.heasarc/uvqs
- Title:
- UV-Bright Quasar Survey (UVQS) DR1 Catalog
- Short Name:
- UVQS
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains data from the first data release (DR1) from the UV-bright Quasar Survey (UVQS) for new z ~ 1 active galactic nuclei (AGN) across the sky. Using simple GALEX UV and WISE near-IR color selection criteria, the authors generated a list of 1,450 primary candidates with FUV < 18.5 mag, that is contained in the HEASARC table (entries with source_sample = 'P'). They obtained discovery spectra, primarily on 3m-class telescopes, for 1,040 of these candidates and confirmed 86% as AGN, with redshifts generally at z > 0.5. Including a small set of observed secondary candidates, the authors report the discovery of 217 AGN with GALEX FUV magnitudes < 18 mag that previously had no reported spectroscopic redshifts. These are excellent potential targets for UV spectroscopy before the end of the Hubble Space Telescope mission. The main data products of UVQS are publicly available through the Mikulski Archive for Space Telescopes (MAST). The authors have performed an all-sky survey for z ~ 1, FUV-bright quasars selected from GALEX and WISE photometry. In several of the observing runs, conditions were unexpectedly favorable and we exhausted the primary candidates at certain right ascension ranges. To fill the remaining observing time, they generated a secondary candidate list. This secondary set of 2,010 candidates is also contained in this HEASARC table (entries with source_sample = 'S'). The authors proceeded to obtain discovery-quality long-slit spectra (i.e., low-dispersion, large-wavelength coverage, modest signal-to-noise ratio (S/N) of their UV-bright Quasar Survey (UVQS) candidates in one calendar year. The principal facilities were: (i) the dual Kast spectrometer on the 3m Shane telescope at the Lick Observatory; (ii) the Boller & Chivens (BCS) spectrometer on the Irenee du Pont 100-inch telescope at the Las Campanas Observatory; and (iii) the Calar Alto Faint Object Spectrograph on the CAHA 2.2-meter telescope at the Calar Alto Observatory (CAHA). They acquired an additional ~20 spectra on larger aperture telescopes (Keck/ESI, MMT/MBC, Magellan/MagE) during twilight or under poor observing conditions. Typical exposure times were limited to < ~200s, with adjustments for fainter sources or sub-optimal observing conditions. Table 3 in the reference paper provides a list of the details of the observations of these candidates. From the total candidates list of 3,460 objects, the authors measured high-quality redshifts (redshift quality flag values of 3 or greater) for 1,121 sources. They assumed that every source with a recessional velocity v<sub>r</sub> = z * c < 500 km s<sup>-1</sup> was "Galactic", which they associate with the Galaxy and members of the Local Group. This included sources where the eigenspectra fits were poor yet a low v<sub>r</sub> was indisputable (e.g., stars). Many of these were assigned z = 0 exactly. The remainder of the UVQS sources were assumed to be extragalactic AGN, and the derived redshift information for these sources (which was given in Table 4 of the reference paper) has been incorporated into this HEASARC representation of UVQS. Finally, there were 93 sources with good-quality spectra for which we cannot the authors could not recover a secure redshift. The majority of these have been previously cataloged as blazars (or BL Lac objects). Table 6 in the reference paper lists the sample of these unknown or insecure redshift objects. This table was created by the HEASARC in April 2017 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/152/25">CDS Catalog J/AJ/152/25</a> files table1.dat, table2.dat, and table4.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/veroncat
- Title:
- VeronCatalogofQuasars&AGN,13thEdition
- Short Name:
- Veron
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table contains the 13th edition of the Catalog of Quasars and Active Galactic Nuclei by Veron-Cetty and Veron, and is an update of the previous versions. As in the previous editions, no information about absorption lines or X-ray properties is given, but absolute magnitides are provided, assuming a Hubble constant H<sub>0</sub> = 71 km/s/Mpc and a deceleration parameter q<sub>0</sub> = 0 (notice the change of cosmology from previous editions in which H<sub>0</sub> was assumed to be 50 km/s/Mpc). The present edition of this catalog contains 133336 quasars, 1374 BL Lac objects and 34231 active galaxies (including 15627 Seyfert 1 galaxies), for a grand total of 168941 objects, significantly more than the number of objects listed in the 12th edition (108080). The 13th edition includes positions and redshifts, as well as photometry (U, B, and V) and 6-cm and 20-cm flux densities, when available. 178 objects once proposed but now rejected as quasars are NOT included in the online version of this catalog: their names and positions are listed in the file <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/258/reject.dat">https://cdsarc.cds.unistra.fr/ftp/cats/VII/258/reject.dat</a>. This HEASARC table also does NOT contain the additional information on gravitationally lensed quasars and quasar pairs listed in Tables 3 and 4 of the published paper: these tables are available in electronic form at the CDS <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/248/">https://cdsarc.cds.unistra.fr/ftp/cats/VII/248/</a> files table2.dat and table3.dat (sic). The present edition of this catalog contains quasars with measured redshift known prior to July 1st, 2009. This online catalog was created by the HEASARC in April 2010 based on machine-readable tables obtained from the CDS (their catalog VII/258, files qso.dat, bllac.dat, and agn.dat). It was last updated in June 2012 to tweak some class values. This is a service provided by NASA HEASARC .
- ID:
- ivo://archive.stsci.edu/wuppe
- Title:
- Wisconsin Ultraviolet Photo-Polarimeter Experiment
- Short Name:
- WUPPE
- Date:
- 22 Jul 2020 21:33:04
- Publisher:
- Space Telescope Science Institute Archive
- Description:
- The Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE) was the spectropolarimetry component of the three ASTRO instruments that flew on Space Shuttle missions in December 1990 and March 1995. A halfwave spectropolarimeter provided medium resolution spectropolarimetry for research into the interstellar medium, hot stars, stars with circumstellar material, interacting binary stars, novae, solar system objects, and active galaxies. A Lyot analyzer obtained low resolution observations of faint targets, but due to calibration problems did not produce scientifically useful data. The WUPPE instrument provides a unique data set, one of the few providing polarimetric data in the ultraviolet portion of the spectrum.
- ID:
- ivo://nasa.heasarc/xshzagncxo
- Title:
- X-Ray Selected High-z AGN Catalog
- Short Name:
- XSHZAGNCXO
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the results from an analysis of the largest high-redshift (z > 3) X-ray-selected active galactic nucleus (AGN) sample to date, combining the Chandra Cosmological Evolution Survey and Chandra Multi-wavelength Project surveys and doubling the previous samples. The sample comprises 209 X-ray-detected AGNs, over a wide range of rest-frame 2-10 keV luminosities log L<sub>X</sub> = 43.3 - 46.0 erg/s. X-ray hardness ratios show that ~39 per cent of the sources are highly obscured, N<sub>H</sub> > 10<sup>22</sup> cm<sup>-2</sup>, in agreement with the ~37 per cent of type-2 AGNs found in this sample based on their optical classification. For ~26 per cent of objects, there are mismatched optical and X-ray classifications. Utilizing the 1/V<sub>max</sub> method, the authors confirm that the comoving space density of all luminosity ranges of AGNs decreases with redshift above z > 3 and up to z ~ 7. With a significant sample of AGNs (N = 27) at z > 4, it is found that both source number counts in the 0.5-2 keV band and comoving space density are consistent with the expectation of a luminosity-dependent density evolution (LDDE) model at all redshifts, while they exclude the luminosity and density evolution (LADE) model. The measured comoving space density of type-1 and type-2 AGNs shows a constant ratio between the two types at z > 3. These results for both AGN types at these redshifts are consistent with the expectations of LDDE model. The high-redshift AGN sample used in this work has been selected from the C-COSMOS X-ray catalog, combining the spectroscopic and photometric information available from the identification catalogue of X-ray C-COSMOS sources (Civano et al. 2011, ApJ, 741, 91; 2012, ApJS, 201, 30) and the ChaMP (Chandra Multi-wavelength Project) X-ray catalog using only the 323 ChaMP ObsIDs overlapping with Sloan Digital Sky Survey (SDSS; Richards et al. 2006, AJ, 131, 2766) DR5 imaging. This table was created by the HEASARC in March 2016 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/445/1430">CDS catalog J/MNRAS/445/1430</a> file tablea1.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/xteassagn
- Title:
- XTE All-Sky Slew Survey AGN Catalog
- Short Name:
- XTEASSAGN
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the RXTE All-Sky Slew Survey Catalog of AGN and AGN candidates. The catalog authors compiled a sample of 95 AGNs which were serendipitously detected in the 3-20 keV band at Galactic latitude |b| > 10 degrees during the RXTE Slew Survey (XSS, Revnivtsev et al., CDS Cat. <J/A+A/418/927>), and utilized it to study the statistical properties of the local population of AGN, including the X-ray luminosity function and absorption distribution. They find that among low X-ray luminosity (L<sub>X</sub> < 10<sup>43.5</sup> erg/s) AGN, the ratio of absorbed (characterized by intrinsic absorption in the range 10<sup>22</sup> cm<sup>-2</sup> < N<sub>H</sub> < 10<sup>24</sup> cm<sup>-2</sup>) and unabsorbed (N<sub>H</sub> < 10<sup>22</sup> cm<sup>-2</sup>) objects is 2:1, while this ratio drops to less than 1:5 for higher luminosity AGN. The summed X-ray output of AGN with L<sub>X</sub> > 10<sup>41</sup> erg/s estimated here is smaller than the earlier estimated total X-ray volume emissivity in the local Universe, suggesting that a comparable X-ray flux may be produced together by lower luminosity AGN, non-active galaxies and clusters of galaxies. The authors also presented a sample of 35 AGN candidates, composed of unidentified XSS sources. Most of these AGN belong to the local population (z < 0.1). For each confirmed AGN source, the following information is provided: AGN class, the count rate in two energy bands (3-8 keV and 8-20 keV), the observed and intrinsic (absorption-corrected) luminosity in the 3 - 20keV band, and the intrinsic absorption column density. For the AGN candidates, composed of unidentified XSS sources, the following information is provided: the count rate in two energy bands (3-8 keV and 8-20 keV), the estimated intrinsic absorption column density, and information about RASS Bright Source Catalog and HEAO A-1 X-ray source counterparts. This table was created by the HEASARC in December 2004 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/423/469">CDS Catalog J/A+A/423/469</a>, table1.dat and table2.dat (the corrected version of 01-Dec-2004). This is a service provided by NASA HEASARC .
- « Previous
- Next »
- 1
- 2
- 3
