Search

Start Over Subject quasars Capability Type Simple Cone Search
351. LAMOST new QSOs in M31 and M33 vicinity
ID:
ivo://CDS.VizieR/J/other/RAA/15.1438
Title:
LAMOST new QSOs in M31 and M33 vicinity
Short Name:
J/other/RAA/15.1
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this work, we report new quasars discovered in fields in the vicinity of the Andromeda (M31) and Triangulum (M33) galaxies with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST, also called the Guo Shou Jing Telescope) during the 2013 observational season, the second year of the regular survey. In total, 1330 new quasars are discovered in an area of ~133{deg}^2^ around M31 and M33. With i magnitudes ranging from 14.79 to 20.0 and redshifts from 0.08 to 4.85, the 1330 new quasars represent a significant increase in the number of identified quasars in fields in the vicinity of M31 and M33. Up to now, there have been a total of 1870 quasars discovered by LAMOST in this area. The much enlarged sample of known quasars in this area can potentially be utilized to construct a precise astrometric reference frame for the measurement of minute proper motions of M31, M33 and their associated substructures, which are vital for understanding the formation and evolution of M31, M33 and the Local Group of galaxies. Moreover, in the sample, there are a total of 45, 98 and 225 quasars with i magnitudes brighter than 17.0, 17.5 and 18.0 respectively. In the aforementioned brightness bins, 15, 35 and 84 quasars are reported here for the first time, and 6, 21 and 81 are reported in our previous work. In addition, 0, 1 and 6 are from the Sloan Digital Sky Survey and 24, 41 and 54 are from the NED database. These bright quasars provide an invaluable sample to study the kinematics and chemistry of the interstellar/intergalactic medium of the Local Group.
352. LAMOST Quasar Survey: quasar properties from DR2&3
ID:
ivo://CDS.VizieR/J/AJ/155/189
Title:
LAMOST Quasar Survey: quasar properties from DR2&3
Short Name:
J/AJ/155/189
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is the second installment for the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) Quasar Survey, which includes quasars observed from 2013 September to 2015 June. There are 9024 confirmed quasars in DR2 and 10911 in DR3. After cross-match with the Sloan Digital Sky Survey (SDSS) quasar catalogs and NED, 12126 quasars are discovered independently. Among them, 2225 quasars were released by SDSS DR12 QSO catalog in 2014 after we finalized the survey candidates. 1801 sources were identified by SDSS DR14 as QSOs. The remaining 8100 quasars are considered as newly founded, and among them, 6887 quasars can be given reliable emission line measurements and the estimated black hole masses. Quasars found in LAMOST are mostly located at low-to-moderate redshifts, with a mean value of 1.5. The highest redshift observed in DR2 and DR3 is 5. We applied emission line measurements to H{alpha}, H{beta}, Mg II, and C IV. We deduced the monochromatic continuum luminosities using photometry data, and estimated the virial black hole masses for the newly discovered quasars. Results are compiled into a quasar catalog, which will be available online.
353. LAMOST quasar survey: quasar properties from the DR1
ID:
ivo://CDS.VizieR/J/AJ/151/24
Title:
LAMOST quasar survey: quasar properties from the DR1
Short Name:
J/AJ/151/24
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present preliminary results of the quasar survey in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) first data release (DR1), which includes the pilot survey and the first year of the regular survey. There are 3921 quasars reliably identified, among which 1180 are new quasars discovered in the survey. These quasars are at low to median redshifts, with a highest z of 4.83. We compile emission line measurements around the H{alpha}, H{beta}, Mg II, and C IV regions for the new quasars. The continuum luminosities are inferred from SDSS photometric data with model fitting, as the spectra in DR1 are non-flux-calibrated. We also compile the virial black hole mass estimates, with flags indicating the selection methods, and broad absorption line quasars. The catalog and spectra for these quasars are also available. Of the 3921 quasars, 28% are independently selected with optical-infrared colors, indicating that the method is quite promising for the completeness of the quasar survey. LAMOST DR1 and the ongoing quasar survey will provide valuable data for studies of quasars.
354. Large area KX quasar catalogue
ID:
ivo://CDS.VizieR/J/MNRAS/424/2876
Title:
Large area KX quasar catalogue
Short Name:
J/MNRAS/424/2876
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of a large area, ~600deg^2^, K-band flux-limited spectroscopic survey for luminous quasars are presented. The survey utilizes the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) in regions of sky within the Sloan Digital Sky Survey (SDSS) footprint. The K-band excess (KX) of all quasars with respect to Galactic stars is exploited in combination with a photometric redshift/classification scheme to identify quasar candidates for spectroscopic follow-up observations. The data contained within this investigation will be able to provide new constraints on the fraction of luminous quasars reddened by dust with E(B-V)<=0.5mag. The spectroscopic sample is defined using the K-band, 14.0<=K<=16.6, and SDSS i-band limits of i=19.5, 19.7 and 22.0 over sky areas of 287, 150 and 196deg^2^, respectively. The survey includes >3200 known quasars from the SDSS and more than 250 additional confirmed quasars from the KX selection. A well-defined subsample of quasars in the redshift interval 1.0<=z<=3.5 includes 1152 objects from the SDSS and 172 additional KX-selected quasars. The quasar selection is >95 per cent complete with respect to known SDSS quasars and >95 per cent efficient, largely independent of redshift and i-band magnitude. The properties of the new KX-selected quasars confirm the known redshift-dependent effectiveness of the SDSS quasar selection and provide a sample of luminous quasars experiencing intermediate levels of extinction by dust. The catalogue represents an important step towards the assembly of a well-defined sample of luminous quasars that may be used to investigate the properties of quasars experiencing intermediate levels of dust extinction within their host galaxies or due intervening absorption line systems.
355. Large Bright Quasar Survey (LBQS) VII
ID:
ivo://CDS.VizieR/J/AJ/122/518
Title:
Large Bright Quasar Survey (LBQS) VII
Short Name:
J/AJ/122/518
Date:
21 Oct 2021
Publisher:
CDS
Description:
The source catalog for the Large Bright Quasar Survey (LBQS) and the FIRST Survey are compared in their regions of overlap to assess the efficiency of the LBQS selection algorithms. In the 270 deg^2^ common to both surveys, the LBQS contains ~100,000 stellar and ~40,000 nonstellar objects, while the FIRST catalog contains ~25,000 sources. Cross-correlation of these lists yields 67 positional coincidences between known LBQS quasars and FIRST sources and an additional 19 stellar and 149 nonstellar positional coincidences with the radio catalog. Spectroscopy of all the stellar matches and two-thirds of the nonstellar matches using the Keck I Telescope and the 6.5 m MMT produces eight new quasars. One BL Lac object, previously misclassified during the LBQS survey is also identified. The straightforward fractional incompleteness of the LBQS determined from this sample is 13%+/-4%, in good agreement with the published estimate of 10%.
356. Large Bright Quasar Survey VI (LBQS)
ID:
ivo://CDS.VizieR/J/AJ/109/1498
Title:
Large Bright Quasar Survey VI (LBQS)
Short Name:
J/AJ/109/1498
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
357. Large Quasar Astrometric Catalogue 2 (LQAC-2)
ID:
ivo://CDS.VizieR/J/A+A/537/A99
Title:
Large Quasar Astrometric Catalogue 2 (LQAC-2)
Short Name:
J/A+A/537/A99
Date:
21 Oct 2021
Publisher:
CDS
Description:
First of all we make a substantial review of the definitions and properties of quasars and AGN (Active Galactic Nuclei), the differenciation of these objects being unclear in the literature and even for specialists. This will serve our purpose when deciding which kinds of objects will be taken into account in our compilation. Then we carry out the cross-identification between the 9 catalogues of quasars chosen for their accuracy and their huge number of objects, using a flag for each of them, and including all the available data related to magnitudes (infrared and optical), radiofluxes and redshifts. We also perform cross identification with external catalogues 2MASS, B1.0 and GSC2.3 in order to complete photometric data of the objects. Moreover we compute the absolute magnitude of our extragalactic objects by taking into account the recent studies concerning the galactic absorption. In addition substantial improvements are brought with respect to the first release of the LQAC (Souchay et al., 2009, Cat. J/A+A/494/799). At first a LQAC name is given for each object based on its equatorial coordinates with respect to the ICRS, following a procedure which creates no ambiguity for identification. At second the equatorial coordinates of the objects are recomputed more accurately according to the algorithms used for the elaboration of the Large Quasar Reference Frame (LQRF) (Andrei et al., 2009, Cat. I/313). At third we introduce a morphological classification for the objects which enables in particular to define clearly if the object is point-like or extended. Our final catalogue, called LQAC-2, contains 187 504 quasars. This is roughly larger than the 113 666 quasars recorded in the first version of the LQAC (Souchay et al., 2009, Cat. J/A+A/494/799) and a little more than the number of quasars recorded in the up-dated version of the Veron Cetty and Veron (2010, Cat. VII/258) catalogue, which was the densest compilation of quasars up to now. In addition to the quantitative and qualitative improvements brought by our compilation, we discuss the homogeneity of the data and carry out statistical analysis concerning the spatial density and the distance to the closest neighbour.
358. Large Quasar Astrometric Catalogue 3 (LQAC-3)
ID:
ivo://CDS.VizieR/J/A+A/583/A75
Title:
Large Quasar Astrometric Catalogue 3 (LQAC-3)
Short Name:
J/A+A/583/A75
Date:
21 Oct 2021
Publisher:
CDS
Description:
From an astrometric point of view, quasars constitute quasi-ideal reference objects in the celestial sphere, with an a priori absence of proper motion. Since the second release of the Large Quasar Astrometric Catalog (LQAC), a large number of quasars have been discovered, in particular with the upcoming new release of the SDSS quasars catalog. Following the same procedure as in the two previous releases of the LQAC, our aim was to compile all the quasars recorded until the present date, with accurate recomputation of their equatorial coordinates in the ICRS and with the maximum of information concerning their physical properties, such as the redshift, the photometry, and the absolute magnitudes.
359. Large Quasar Astrometric Catalogue (LQAC)
ID:
ivo://CDS.VizieR/J/A+A/494/799
Title:
Large Quasar Astrometric Catalogue (LQAC)
Short Name:
J/A+A/494/799
Date:
21 Oct 2021
Publisher:
CDS
Description:
The very large and increasing number of quasars reckoned from various sky surveys leads to a large quantity of data which brings various and inhomogeneous information in the fields of astrometry, photometry, radioastronomy and spectroscopy. In this paper, we describe our work that aims to make available a general compilation of the largest number of recorded quasars obtained from all the available catalogues, with their best position estimates, and providing physical information at both optical and radio wavelengths.
360. Las Campanas Redshift Survey
ID:
ivo://CDS.VizieR/VII/203
Title:
Las Campanas Redshift Survey
Short Name:
VII/203
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Las Campanas Redshift Survey (LCRS) consists of 26,418 redshifts of galaxies selected from a CCD-based catalog obtained in the R band. The survey covers over 700deg^2 in six strips, each 1.5x80deg, three each in the north and south Galactic caps. The median redshift in the survey is about 30,000km/s. Essential features of the galaxy selection and redshift measurement methods are described and tabulated here. These details are important for subsequent analysis of the LCRS data. Two-dimensional representations of the redshift distributions reveal many repetitions of voids, on the scale of about 5000km/s, sharply bounded by large walls of galaxies as seen in nearby surveys. Statistical investigations of the mean galaxy properties and of clustering on the large scale are reported elsewhere. These include studies of the luminosity function, power spectrum in two and three dimensions, correlation function, pairwise velocity distribution, identification of large-scale structures, and a group catalog.