Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Quasar Sample

Abstract

We describe the algorithm for selecting quasar candidates for optical spectroscopy in the Sloan Digital Sky Survey. Quasar candidates are selected via their non-stellar colors in "ugriz" broad-band photometry, and by matching unresolved sources to the FIRST radio catalogs. The automated algorithm is sensitive to quasars at all redshifts lower than z=5.8. Extended sources are also targeted as low-redshift quasar candidates in order to investigate the evolution of Active Galactic Nuclei (AGN) at the faint end of the luminosity function. Nearly 95% of previously known quasars are recovered (based on 1540 quasars in 446 square degrees). The overall completeness, estimated from simulated quasars, is expected to be over 90%, whereas the overall efficiency (quasars:quasar candidates) is better than 65%. The selection algorithm targets ultraviolet excess quasars to i^*=19.1 and higher-redshift (z>3) quasars to i^*=20.2, yielding approximately 18 candidates per square degree. In addition to selecting ``normal'' quasars, the design of the algorithm makes it sensitive to atypical AGN such as Broad Absorption Line quasars and heavily reddened quasars.

arXiv comment62 pages, 15 figures (8 color), 8 tables. Accepted by AJ. For a version with higher quality color figures, see http://archive.stsci.edu/sdss/quasartarget/RichardsGT_qsotarget.preprint.ps

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• Cataclysmic Variables from SDSS VII. The Seventh Year (2006)
• DES J0454-4448: Discovery of the First Luminous z > 6 Quasar from the Dark Energy Survey
• Constraining Gravity at the Largest Scales through CMB Lensing and Galaxy Velocities
• Long-Term X-ray Variability of Typical Active Galactic Nuclei in the Distant Universe
• Cosmic Cartography of the Large-Scale Structure with Sloan Digital Sky Survey Data Release 6
• VDES J2325-5229 a z=2.7 gravitationally lensed quasar discovered using morphology independent supervised machine learning
• GALEX far-UV color selection of UV-bright high-redshift quasars
• High-Redshift QSOs in the SWIRE Survey and the z~3 QSO Luminosity Function
• Mean-flux Regulated PCA Continuum Fitting of SDSS Lyman-alpha Forest Spectra
• Metals and Dust in Intermediate-redshift Damped Ly-alpha Galaxies
• Major mergers are not the dominant trigger for high-accretion AGNs at z = 2
• Detections of the 2175 ÅDust Feature at 1.4z 1.5 from the Sloan Digital Sky Survey
• Chemical abundances of distant extremely metal-poor unevolved stars
• Rest-frame Optical Spectra and Black Hole Masses of 3<z<6 Quasars
• Eight-Dimensional Mid-Infrared/Optical Bayesian Quasar Selection
• Cross-correlating Planck CMB lensing with SDSS: Lensing-lensing and galaxy-lensing cross-correlations
• Photometric redshift requirements for lens galaxies in galaxy-galaxy lensing analyses
• Catalogues of Active Galactic Nuclei From Gaia and unWISE Data
• A census of ionized gas outflows in type 1 AGNs: gas outflows in AGNs. V
• BASS XXV: DR2 Broad-line Based Black Hole Mass Estimates and Biases from Obscuration
• Modelling type 1 quasar colours in the era of Rubin and Euclid
• Precious Metals in SDSS Quasar Spectra I: Tracking the Evolution of Strong, 1.5 < z < 4.5 CIV Absorbers with Thousands of Systems
• Stellar Populations of Elliptical Galaxies in the Local Universe
• A Spectroscopic Survey of Faint Quasars in the SDSS Deep Stripe: I. Preliminary Results from the Co-added Catalog
• Intrinsic alignments of BOSS LOWZ galaxies II: Impact of shape measurement methods
• The Time Domain Spectroscopic Survey: Changing-Look Quasar Candidates from Multi-Epoch Spectroscopy in SDSS-IV
• Where are the Luminous Red Galaxies (LRGs)? Using correlation measurements and lensing to relate LRGs to dark matter halos
• Detection of Rest-frame Optical Lines from X-shooter Spectroscopy of Weak Emission Line Quasars
• One thousand cataclysmic variables from the Catalina Real-time Transient Survey
• A Systematic Search for Periodically Varying Quasars in Pan-STARRS1: An Extended Baseline Test in Medium Deep Survey Field MD09
• Quasars in the COSMOS Field
• LoTSS/HETDEX: Optical quasars I. Low-frequency radio properties of optically selected quasars
• Optical Variability of Narrow and Broad line Seyfert 1 galaxies
• Structure and morphology of the MATLAS dwarf galaxies and their central nuclei
• A catalogue of cataclysmic variables from 20 years of the Sloan Digital Sky Survey with new classifications, periods, trends and oddities
• Evidence that the AGN dominates the radio emission in z ~ 1 radio-quiet quasars
• Bayesian High-Redshift Quasar Classification from Optical and Mid-IR Photometry
• Faint High Latitude Carbon Stars Discovered by the Sloan Digital Sky Survey: Methods and Initial Results
• Testing adiabatic contraction with SDSS elliptical galaxies
• The GALEX Time Domain Survey I. Selection and Classification of Over a Thousand UV Variable Sources
• Cosmological constraints from galaxy-lensing cross correlations using BOSS galaxies with SDSS and CMB lensing
• The Discovery of Three New z>5 Quasars in the AGN and Galaxy Evolution Survey
• Topology of structure in the Sloan Digital Sky Survey: model testing
• Population Synthesis Studies of Close Binary Systems Using a Variable Common Envelope Efficiency Parameter: I. Dependence upon Secondary Mass
• Search for CII Emission on Cosmological Scales at Redshift Z~2.6
• Discovery of New Ultracool White Dwarfs in the Sloan Digital Sky Survey
• New Close Binary Systems from the SDSS-I (Data Release Five) and the Search for Magnetic White Dwarfs in Cataclysmic Variable Progenitor Systems
• The radio loudness of SDSS quasars from the LOFAR Two-metre Sky Survey: ubiquitous jet activity and constraints on star formation
• Compact steep-spectrum sources as the parent population of flat-spectrum radio-loud NLS1s
• Star-galaxy separation strategies for WISE-2MASS all-sky infrared galaxy catalogs
• Type 1 AGN at low z. III. The optical narrow line ratios
• X-ray Insights into the Nature of Weak Emission-Line Quasars at High Redshift
• First results from the Canada-France High-z Quasar Survey: Constraints on the z=6 quasar luminosity function and the quasar contribution to reionization
• Quasar candidate selection and photometric redshift estimation based on SDSS and UKIDSS data
• VLT LBG Redshift Survey II: Interactions between galaxies and the IGM at z ~3
• Cool DZ white dwarfs in the SDSS
• A Simple Likelihood Method for Quasar Target Selection
• Dual supermassive black holes at close separation revealed by the Hyper Suprime-Cam Subaru Strategic Program
• The Atacama Cosmology Telescope: Detection of Sunyaev-Zel'dovich Decrement in Groups and Clusters Associated with Luminous Red Galaxies
• The Spatial Clustering of Low Luminosity AGN
• The large area KX quasar catalogue: I. Analysis of the photometric redshift selection and the complete quasar catalogue
• The SDSS u-band Galaxy Survey: Luminosity functions and evolution
• Panchromatic Properties of 99,000 Galaxies Detected by SDSS, and (some by) ROSAT, GALEX, 2MASS, IRAS, GB6, FIRST, NVSS and WENSS Surveys
• Measuring Quasar Variability with Pan-STARRS1 and SDSS
• Discovery of an unidentified Fermi object as a black widow-like millisecond pulsar
• What triggers galaxy transformations? The environments of post-starburst galaxies
• A new infrared color criterion for the selection of 0<z<7 AGN: application to deep fields and implications for JWST surveys
• Optical/near-infrared selection of red QSOs: Evidence for steep extinction curves towards galactic centers?
• Correlations of Quasar Optical Spectra with Radio Morphology
• Non-detection of a statistically anisotropic power spectrum in large-scale structure
• A simple test for the existence of two accretion modes in Active Galactic Nuclei
• Intrinsic alignments in redMaPPer clusters -- I. Central galaxy alignments and angular segregation of satellites
• X-Ray-Emitting Stars Identified from the ROSAT All-Sky Survey and the Sloan Digital Sky Survey
• Systematic effects in large-scale angular power spectra of photometric quasars and implications for constraining primordial nongaussianity
• Variable Faint Optical Sources Discovered by Comparing POSS and SDSS Catalogs
• Mean and Extreme Radio Properties of Quasars and the Origin of Radio Emission
• Constraints on cosmological models from lens redshift data
• Precision cluster mass determination from weak lensing
• The contribution of spin to jet-disk coupling in black holes
• Automated physical classification in the SDSS DR10. A catalogue of candidate Quasars
• Bivariate Galaxy Luminosity Functions in the Sloan Digital Sky Survey
• The VIMOS Public Extragalactic Redshift Survey (VIPERS). A Support Vector Machine classification of galaxies, stars and AGNs
• Twenty-three new ultra-cool subdwarfs from the Sloan Digital Sky Survey
• The UV Properties of SDSS Selected Quasars
• Quasar candidates selection in the Virtual Observatory era
• Evolution of the Colour--Radius Relation and the Morphology--Radius Relation in the SDSS Galaxy Clusters
• Unusual quasars from the Sloan Digital Sky Survey selected by means of Kohonen self-organising maps
• SDSS J094533.99+100950.1 - the remarkable weak emission line quasar
• Gravitational Lensing Statistics in Universes Dominated by Dark Energy
• Exploring Changing-look Active Galactic Nuclei with the Sloan Digital Sky Survey V: First Year Results
• The VIMOS VLT Deep Survey: the faint type-1 AGN sample
• Dust Reddened Quasars in FIRST and UKIDSS: Beyond the Tip of the Iceberg
• SDSS-IV eBOSS Spectroscopy of X-ray and WISE AGN in Stripe 82X: Overview of the Demographics of X-ray and Mid-Infrared Selected Active Galactic Nuclei
• The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Quasar Survey: the 4th and 5th Data Release
• Acceleration and Substructure Constraints in a Quasar Outflow
• The spatial clustering of ROSAT All-Sky Survey Active Galactic Nuclei IV. More massive black holes reside in more massive dark matter halos
• A new extensive catalog of optically variable AGN in the GOODS Fields and a new statistical approach to variability selection
• Nature and evolution of powerful radio galaxies and their link with the quasar luminosity function
• Composite Spectral Energy Distributions and Infrared-Optical Colors of Type 1 and Type 2 Quasars
• Semi-analytic forecasts for JWST -- V. AGN luminosity functions and helium reionization at z = 2-7
• Probing gravity with a joint analysis of galaxy and CMB lensing and SDSS spectroscopy
• Statistical Detection of the HeII Transverse Proximity Effect: Evidence for Sustained Quasar Activity for $>$25 Million Years
• Tracing the evolution of Active Galactic Nuclei host galaxies over the last 9 Gyrs of Cosmic time
• Morphological Classification of Galaxies by Shapelet Decomposition in the Sloan Digital Sky Survey
• The Sloan Digital Sky Survey Quasar Lens Search. IV. Statistical Lens Sample from the Fifth Data Release
• SDSS J0246-0825: A New Gravitationally Lensed Quasar from the Sloan Digital Sky Survey
• Extreme star formation events in quasar hosts over $0.5<\text{z}<4$
• A quasar reddened by a sub-parsec sized, metal-rich and dusty cloud in a damped Lyman-alpha absorber at z=2.13
• The Intrinsic Fractions and Radio Properties of Low Ionization Broad Absorption Line Quasars
• Data Mining for Dwarf Novae in SDSS, GALEX and Astrometric Catalogues
• Improved optical mass tracer for galaxy clusters calibrated using weak lensing measurements
• The Composite Spectrum of BOSS Quasars Selected for Studies of the Lyman-alpha Forest
• A Census of Object Types and Redshift Estimates in the SDSS Photometric Catalog from a Trained Decision-Tree Classifier
• Optical spectroscopy of BL Lacertae objects. Broad lines, companion galaxies and redshift lower limits
• The Faint End of the Quasar Luminosity Function at z~4
• Gravitationally Lensed Quasars in Gaia: I. Resolving Small-Separation Lenses
• Discovery of 16 New z ~ 5.5 Quasars : Filling in the Redshift Gap of Quasar Color Selection
• Clustering on very small scales from a large sample of confirmed quasar pairs: Does quasar clustering track from Mpc to kpc scales?
• A Search for Kilonovae in the Dark Energy Survey
• SDSS J1335+0118: A New Two-Image Gravitational Lens
• The age structure of the Milky Way's halo
• Are red 2MASS QSOs young?
• White dwarf-main sequence binaries from LAMOST: the DR5 catalogue
• A Balmer-line Broad Absorption Line Quasar
• On the discovery of stars, quasars, and galaxies in the Southern Hemisphere with S-PLUS DR2
• Multiepoch Sky Surveys and the Lifetime of Quasars
• Candidate Disk Wide Binaries in the Sloan Digital Sky Survey
• Synchronized Co-evolution between Supermassive Black Holes and Galaxies Over the Last Seven Billion Years as Revealed by the Hyper Suprime-Cam
• Average Properties of a Large Sample of z_abs ~ z_em associated Mg II Absorption Line Systems
• SDSS J0806+2006 and SDSS J1353+1138: Two New Gravitationally Lensed Quasars from the Sloan Digital Sky Survey
• The Extremely Luminous Quasar Survey (ELQS) in the SDSS footprint I.: Infrared Based Candidate Selection
• The first high-redshift changing-look quasars
• Correlation between galaxies and QSO in the SDSS:na signal from gravitational lensing magnification?
• The population of white dwarf-main sequence binaries in the SDSS DR 12
• Two close Large Quasar Groups of size ~ 350 Mpc at z ~ 1.2
• Supermassive black holes in disk-dominated galaxies outgrow their bulges and co-evolve with their host galaxies
• An ultra-luminous quasar at z=5.363 with a ten billion solar mass black hole and a Metal-Rich DLA at z~5
• Finding rare objects and building pure samples: Probabilistic quasar classification from low resolution Gaia spectra
• Towards Detecting The 2175-Å Dust Feature Associated With Strong High Redshift Mg ßII Absorption Lines
• Five New High-Redshift Quasar Lenses from the Sloan Digital Sky Survey
• Photometric selection and redshifts for quasars in the Kilo-Degree Survey Data Release 4
• Combining Dark Energy Survey Science Verification Data with Near Infrared Data from the ESO VISTA Hemisphere Survey
• A tale of two feedbacks: star-formation in the host galaxies of radio-AGN
• Two Additions to the New Class of Low Accretion-Rate Magnetic Binaries
• A UV to Mid-IR Study of AGN Selection
• Orientation effects in quasar spectra: The broad- and narrow-line regions
• Ultraviolet variability of quasars: dependence on the accretion rate
• Catalog of quasars from the Kilo-Degree Survey Data Release 3
• A Census of Broad-Line Active Galactic Nuclei in Nearby Galaxies: Coeval Star Formation and Rapid Black Hole Growth
• Probing the Radio Loud/Quiet AGN dichotomy with quasar clustering
• Ultraluminous Infrared Galaxies in the AKARI All Sky Survey
• Is there any evidence that ionised outflows quench star formation in type 1 quasars at z<1?
• Principal Component Analysis of SDSS Stellar Spectra
• ROXA: a new multi-frequency selected large sample of blazars with SDSS and 2dF optical spectroscopy
• Fundamental differences in the radio properties of red and blue quasars: Insight from the LOFAR Two-metre Sky Survey (LoTSS)
• Anomalously Steep Reddening Law in Quasars: An Exceptional Example Observed in IRAS14026+4341
• A Catalog of Very Isolated Galaxies from the SDSS Data Release 1
• The Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) Quasar Survey: Quasar Properties from Data Release Six to Nine
• The clustering of X-ray selected AGN at z=0.1
• The Distribution of Secondary Masses in Post-Common Envelope Binaries: A Potential Test of Disrupted Magnetic Braking
• VLT+UVES Spectroscopy of the CaII LoBAL Quasar SDSS J030000.56+004828.0
• The Probability Distribution of the Lya transmitted flux from a sample of SDSS quasars
• SDSS J1650+4251: A New Gravitational Lens
• The Largest X-ray Selected Sample of z>3 AGNs: C-COSMOS & ChaMP
• The Magellan Uniform Survey of Damped Lyman alpha Systems II: Paucity of Strong Molecular Hydrogen Absorption
• Do Some AGN Lack X-ray Emission?
• Discovery of Four Gravitationally Lensed Quasars from the Sloan Digital Sky Survey
• Detection of Intergalactic HeII Absorption at Redshift 3.5
• Eight New Quasar Lenses from the Sloan Digital Sky Survey Quasar Lens Search
• Astrometric Redshifts for Quasars
• White dwarf-main sequence binaries from LAMOST: the DR1 catalogue
• Selecting Quasar Candidates by a SVM Classification System
• SDSSJ102111.02+491330.4: A Newly Discovered Gravitationally Lensed Quasar
• The Large Sky Area Multi-Object Fiber Spectroscopic Telescope Quasar Survey: Quasar Properties from First Data Release
• A High Yield of New Sightlines for the Study of Intergalactic Helium: Far-UV-Bright Quasars from SDSS, GALEX, and HST
• Detection of Quasar Feedback from the Thermal Sunyaev-Zel'dovich Effect in Planck
• Variability and Multiwavelength Detected AGN in the GOODS Fields
• Model Atmosphere Analysis of the Weakly Magnetic DZ White Dwarf G165-7
• Spectral Variability of Quasars in the Sloan Digital Sky Survey. II: The C IV Line
• AGN and QSOs in the eROSITA All-Sky Survey -- Part I: Statistical properties
• Eddington ratios of faint AGN at intermediate redshift: Evidence for a population of half-starved black holes
• Candidate Isolated Neutron Stars and Other Optically Blank X-ray Fields Identified from the ROSAT All-Sky and Sloan Digital Sky Surveys
• Radio-Selected Quasars in the Sloan Digital Sky Survey
• Co-evolution of Extreme Star Formation and Quasar: hints from {\it Herschel} and the Sloan Digital Sky Survey
• Finding the brightest cosmic beacons in the Southern Hemisphere
• Radiative Efficiency of Disk Accretion in Individual SDSS QSOs
• Additional Ultracool White Dwarfs Found in the Sloan Digital Sky Survey
• Finding Quasars behind the Galactic Plane. I. Candidate Selections with Transfer Learning
• The UV, Optical, and IR Properties of SDSS Sources Detected by GALEX
• A Herschel Study of 24 micron-Selected AGNs and Their Host Galaxies
• Determining the Lensing Fraction of SDSS Quasars: Methods and Results from the EDR
• High-redshift Extreme Variability Quasars from Sloan Digital Sky Survey Multi-Epoch Spectroscopy
• Quasar Photometric Redshifts and Candidate Selection: A New Algorithm Based on Optical and Mid-Infrared Photometric Data
• Spectral Evolution in High Redshift Quasars from the Final BOSS Sample
• The Optical and Near-Infrared Properties of 2837 Quasars in the UKIRT Infrared Deep Sky Survey (UKIDSS)
• The origin of single low-mass WDs: another problem that consequential angular momentum loss in CVs might solve
• Two New Gravitationally Lensed Double Quasars from the Sloan Digital Sky Survey
• Discovering Gravitational Lenses Through Measurements Of Their Time Delays
• An Unbiassed Census of Active Galactic Nuclei in the Two Micron All Sky Survey
• SDSS 0956+5128: A Broad-line Quasar with Extreme Velocity Offsets
• Discovery of a Gravitationally Lensed Quasar from the Sloan Digital Sky Survey: SDSS J133222.62+034739.9
• A Nearby Old Halo White Dwarf Candidate from the Sloan Digital Sky Survey
• The WISE-2MASS Survey: Red Quasars Into the Radio Quiet Regime
• The effect of dust bias on the census of neutral gas and metals in the high-redshift Universe due to SDSS-II quasar colour selection
• The Lyman continuum escape fraction and the Mean Free Path of hydrogen ionizing photons for bright z~4 QSOs from SDSS DR14
• Characterisation of Sloan Digital Sky Survey Stellar Photometry
• Large Scale Clustering of Sloan Digital Sky Survey Quasars: Impact of the Baryon Density and the Cosmological Constant
• Measuring large-scale structure with quasars in narrow-band filter surveys
• The fraction and kinematics of broad absorption line quasars across cosmic time
• The extended High A(V) Quasar Survey: Searching for dusty absorbers toward mid-infrared selected quasars
• Spectral Properties of Galaxies in Void Regions
• Pan-STARRS1 variability of XMM-COSMOS AGN. I. Impact on photometric redshifts
• Robust Identification of Active Galactic Nuclei through HST Optical Variability in GOODS-S: Comparison with the X-ray and mid-IR Selected Samples
• Luminous Red Galaxy Population in Clusters at $0.2\le z\le 0.6$
• A Metal-Strong and Dust-Rich Damped \lya Absorption System toward the Quasar SDSS J115705.52+615521.7
• An FeLoBAL Binary Quasar
• The 2QDES Pilot : The luminosity and redshift dependence of quasar clustering
• The QUEST-La Silla AGN Variability Survey: selection of AGN candidates through optical variability
• Random Forests as a viable method to select and discover high redshift quasars
• The Extremely Luminous Quasar Survey in the Pan-STARRS 1 Footprint (PS-ELQS)
• The Time-Domain Spectroscopic Survey: Target Selection for Repeat Spectroscopy
• Mass models and environment of the new quadruply lensed quasar SDSS J1330+1810
• The dust content of damped Lyman-alpha systems in the Sloan Digital Sky Survey
• Clustering of Lyman-alpha Emitters Around Quasars at $z\sim 4$
• A Study of Quasar Selection in the Dark Energy Survey Supernova fields
• Cross-Correlation of the Extragalactic Gamma-ray Background with Luminous Red Galaxies
• A Snapshot Survey for Gravitational Lenses Among z>=4.0 Quasars: II. Constraints on the 4.0<z<4.5 Quasar Population
• The near-IR properties and continuum shapes of high redshift quasars from the Sloan Digital Sky Survey
• A Synoptic, Multiwavelength Analysis of a Large Quasar Sample
• The LAMOST Survey of Background Quasars in the Vicinity of the Andromeda and Triangulum Galaxies -- II. Results from the Commissioning Observations and the Pilot Surveys
• The QUEST-La Silla AGN Variability Survey
• Statistics of Galactic-Scale Quasar Pairs at Cosmic Noon
• The most luminous AGN do not produce the majority of the detected stellar-mass black hole binary mergers in the local Universe
• The Redshift of a Lensing Galaxy in PMN J0134-0931
• Narrow absorption line variability in repeat quasar observations from the Sloan Digital Sky Survey
• Probing the Structure and Evolution of BASS AGN through Eddington Ratios
• The soft X-ray properties of quasars in the Sloan Digital Sky Survey
• Disk-Jet Connection in Active Supermassive Black Holes in the Standard Accretion Disk Regime
• Finding New High-Redshift Quasars by Asking the Neighbours
• Fundamental differences in the properties of red and blue quasars: measuring the reddening and accretion properties with X-shooter
• Discovery of the most ultra-luminous QSO using Gaia, SkyMapper and WISE
• Revisiting the Lensed Fraction of High-Redshift Quasars
• Dusty MgII absorbers: population statistics, extinction curves and gamma-ray burst sightlines
• The Sloan Digital Sky Survey
• The ISO-2MASS AGN survey: On the type-1 sources
• Fundamental differences in the radio properties of red and blue quasars: kiloparsec-scale structures revealed by e-MERLIN
• CatNorth: An Improved Gaia DR3 Quasar Candidate Catalog with Pan-STARRS1 and CatWISE
• Gaia Data Release 3: The first Gaia catalogue of variable AGN
• A New Quadruply Lensed Quasar: SDSSJ125107.57+293540.5
• Photometric Catalogue of Quasars and Other Point Sources in the Sloan Digital Sky Survey
• Quasar-Galaxy Clustering through Projected Galaxy Counts at z=0.6-1.2
• Placing High-Redshift Quasars in Perspective: a Catalog of Spectroscopic Properties from the Gemini Near Infrared Spectrograph -- Distant Quasar Survey
• Caught in the Act: Discovery of a Physical Quasar Triplet
• Photometric Classification of quasars from RCS-2 using Random Forest
• Estimation of Absolute Magnitude-dependent Galactic Model Parameters In Intermediate Latitude With SDSS and SCUSS
• Color-redshift Relations and Photometric Redshift Estimations of Quasars in Large Sky Surveys
• ChAInGeS: The Chandra Arp Interacting Galaxies Survey
• Photometric Selection of QSO Candidates From GALEX Sources
• Eight new quasars discovered by LAMOST in one extragalactic field
• Ten More New Sightlines for the Study of Intergalactic Helium, and Hundreds of Far-UV-Bright Quasars, from SDSS, GALEX, and HST
• Extreme Variability Quasars in Their Various States. I: The sample selection and composite SDSS spectra
• The Transparency of Galaxy Clusters
• Evidence for higher black hole spin in radio-loud quasars
• The co-evolution of black hole growth and star formation from a cross-correlation analysis between quasars and the cosmic infrared background
• Seeing in the dark -- I. Multi-epoch alchemy
• SDSS J094604.90+183541.8: A Gravitationally Lensed Quasar at z=4.8
• Downsizing of supermassive black holes from the SDSS quasar survey (II). Extension to z~4
• The Evolution of Post-Starburst Galaxies from $z\sim 1$ to the Present
• A New Technique for Galaxy Photometric Redshifts in the Sloan Digital Sky Survey
• Use of neural networks for the identification of new z>=3.6 QSOs from FIRST-SDSS DR5
• The rapid transition from star-formation to AGN dominated rest-frame UV light at z ~ 4
• The optical variability of SDSS quasars from multi-epoch spectroscopy: I. Results from 60 quasars with $\ge$ six-epoch spectra
• A quasar hiding behind two dusty absorbers. Quantifying the selection bias of metal-rich, damped Lyman-alpha absorption systems
• Galaxies with Background QSOs, I: A Search for Strong Galactic H-alpha Lines
• Probing Spectroscopic Variability of Galaxies & Narrow-Line Active Galactic Nuclei in the Sloan Digital Sky Survey
• The Extremely Luminous Quasar Survey (ELQS) in the Sloan Digital Sky Survey footprint. II. The North Galactic Cap Sample
• An Apparent Redshift Dependence of Quasar Continuum: Implication for Cosmic Dust Extinction?
• The 9 and 18 Micron Luminosity Function of Various Types of Galaxies with AKARI: Implication for the Dust Torus Structure of AGN
• New Quasars Detected via Variability in the QUEST1 Survey
• Constraining the Gravitational Lensing of $z\gtrsim 6$ Quasars from their Proximity Zones
• Fundamental Plane of BOSS galaxies: Correlations with galaxy properties, density field and impact on RSD measurements
• Morphological Classification of Galaxies by Shapelet Decomposition in the Sloan Digital Sky Survey II: Multiwavelength Classification
• The Spectral Energy Distributions of Red 2MASS AGN
• Critical Examinations of QSO Redshift Periodicities and Associations with Galaxies in Sloan Digital Sky Survey Data
• Statistical Searches for Microlensing Events in Large, Non-Uniformly Sampled Time-Domain Surveys: A Test Using Palomar Transient Factory Data
• Strong [O III] Objects Among SDSS Broad-Line Active Galaxies
• The Quasar Mass-Luminosity Plane II: High Mass Turnoff Evolution and a Synchronization Puzzle
• The SDSS-XMM Quasar Sample: First Results
• The Effect of Minor and Major Mergers on the Evolution of Low Excitation Radio Galaxies
• The Time-Domain Spectroscopic Survey: Understanding the Optically Variable Sky with SEQUELS in SDSS-III
• Compact E+A Galaxies as a Progenitor of Massive Compact Quiescent Galaxies at 0.2<z< 0.8
• Discovery of Four Doubly Imaged Quasar Lenses from the Sloan Digital Sky Survey
• A very bright i=16.44 quasar in the `redshift desert' discovered by LAMOST
• The Effect of Variability on the Estimation of Quasar Black Hole Masses
• A New X-Ray Analysis of the Open Cluster Blanco 1 Using Wide-Field BVIc Photometric and Proper Motion Surveys
• Do broad absorption line quasars live in different environments from ordinary quasars?
• Observational evidence favors a static universe
• Powerful Radio-Loud Quasars are Triggered by Galaxy Mergers in the Cosmic Bright Ages
• A systematic search for hidden type 1 AGNs: gas kinematics and scaling relations
• The Cosmic Web Around The Brightest Galaxies During The Epoch Of Reionization
• X-ray and optical properties of Broad Absorption Line Quasars in the Canada-France-Hawaii Telescope Legacy Survey
• Seoul National University Bright Quasar Survey in Optical (SNUQSO) I: First Phase Observations and Results
• Intervening Mg II absorption systems from the SDSS DR12 quasar spectra
• Topology of Luminous Red Galaxies from the Sloan Digital Sky Survey
• The Color Selection of Quasars from Redshifts 5 to 10: Cloning and Discovery
• Calibrating Milky Way dust extinction using cosmological sources
• Selection constraints on high redshift quasar searches in the VISTA kilo-degree infrared galaxy survey
• A Search for Nitrogen Enriched Quasars in the Sloan Digital Sky Survey Early Data Release
• A Lyman-alpha-only AGN from the Sloan Digital Sky Survey
• Estimating Spectroscopic Redshifts by Using k Nearest Neighbors Regression I. Description of Method and Analysis
• Bright Lyman Break Galaxy Candidates in the Sloan Digital Sky Survey First Data Release
• A Cross-correlation Analysis of AGN and Galaxies using Virtual Observatory: Dependence on Virial Mass of Super-Massive Black Hole
• The ALHAMBRA survey: Discovery of a faint QSO at z = 5.41
• Discovering the missing 2.2<z<3 quasars by combining optical variability and optical/near-IR colors
• Quasars as a tracer of large-scale structures in the distant universe
• A Mote in Andromeda's Disk: a Misidentified Periodic AGN Behind M31
• Connecting Low- and High-Redshift Weak Emission-Line Quasars via HST Spectroscopy of Ly$\alpha$ Emission
• Distances of Quasars and Quasar-Like Galaxies: Further Evidence that QSOs may be Ejected from Active Galaxies
• Mid-Infrared Selected Quasars I: Virial Black Hole Mass and Eddington Ratios
• The formation of bulges and black holes: lessons from a census of active galaxies in the SDSS
• On the use of photometric redshifts for X-ray selected AGNs
• Measuring the luminosity and virial black hole mass dependence of quasar-galaxy clustering at z ~ 0.8
• Intermediate Inclinations of Type 2 Coronal-Line Forest AGN
• Deep Extragalactic VLBI-Optical Survey (DEVOS) II. Efficient VLBI detection of SDSS quasars
• The ensemble optical variability of type-1 AGN in the Sloan Digital Sky Survey Data Release 7
• Discovering Strongly-lensed QSOs From Unresolved Light Curves
• Red AGN in XMM-Newton/SDSS fields
• An Unobscured type II quasar candidate: SDSS J012032.19-005501.9
• The optically-selected 1.4-GHz quasar luminosity function below 1 mJy
• Stochastic Processes as the Origin of the Double-Power Law Shape of the Quasar Luminosity Function
• Dust accretion and destruction in galaxy groups and clusters
• A Novel Method to Identify AGNs Based on Emission Line Excess and the Nature of Low-luminosity AGNs in the Sloan Digital Sky Survey: II - Nature of Low-luminosity AGNs
• Six Peaks Visible in the Redshift Distribution of 46,400 SDSS Quasars Agree with the Preferred Redshifts Predicted by the Decreasing Intrinsic Redshift Model
• Host Dark Matter Halos of SDSS Red and Blue Quasars: No Significant Difference in Large-scale Environment
• ASPECT: A spectra clustering tool for exploration of large spectral surveys
• Proof of CMB-driven X-ray brightening of high-z radio galaxies
• Fe II and Mg II in Luminous, Intermediate-Redshift Narrow-line Seyfert 1 Galaxies from the Sloan Digital Sky Survey
• Wide Area VISTA Extra-galactic Survey (WAVES): Unsupervised star-galaxy separation on the WAVES-Wide photometric input catalogue using UMAP and $\mathrm{HDBSCAN}$
• A Search for Planetary Nebulae With the SDSS: the outer regions of M31
• Source Matching in the SDSS and RASS: Which Galaxies are Really X-ray Sources?
• Neural-network selection of high-redshift radio quasars, and the luminosity function at z~4
• Quasar UV Luminosity Function at $3.5<z<5.0$ from SDSS Deep Imaging Data
• The miniJPAS survey quasar selection II: Machine learning classification with photometric measurements and uncertainties
• Characterization of Dwarf Novae Using SDSS Colors
• MALS SALT-NOT survey of MIR-selected powerful radio-bright AGN at 0<z<3.5
• New Clues to Jet Launching: The inner disks in radio loud quasars may be more stable
• Determining the fraction of reddened quasars in COSMOS with multiple selection techniques from X-ray to radio wavelengths
• Concordance between observations and simulations in the evolution of the mass relation between supermassive black holes and their host galaxies
• The Knotty Question of the Jet of PKS B1421-490
• Identifying High Metallicity M Giants at Intragroup Distances with SDSS
• A Quasar Without Broad Lyman-alpha Emission
• Spectroscopic classification of a complete sample of astrometrically-selected quasar candidates using Gaia DR2
• A slitless spectroscopic survey for quasars near quasars
• SDSS J133401.39+331534.3: A New Subarcsecond Gravitationally Lensed Quasar
• ULISSE: A Tool for One-shot Sky Exploration and its Application to Active Galactic Nuclei Detection
• Searching for Super-Eddington Quasars using a Photon Trapping Accretion Disc Model
• Kpc-scale Radio Structure in $z\sim 0.25$ Radio-Quiet QSOs
• A Novel Method to Identify AGNs Based on Emission Line Excess and the Nature of Low-luminosity AGNs in the Sloan Digital Sky Survey: I - A Novel Method
• No Confirmed New Isolated Neutron Stars In The SDSS Data Release 4
• The composite X-ray spectra of radio-loud and radio-quiet SDSS quasars
• Neutral gas density in Damped Lyman Alpha systems
• VLT + UVES Spectroscopy of the Low-Ionization Intrinsic Absorber in SDSS J001130.56+005550.7
• Constraining the Low-Mass End of the Black Hole Mass Function and the Active Fraction of the Intermediate-mass Black Holes
• The quasar-galaxy cross SDSS J1320+1644: A probable large-separation lensed quasar
• Empirical Constraints on Core Collapse Supernova Yields using Very Metal Poor Damped Lyman Alpha Absorbers
• Current star formation in early-type galaxies and the K+A phenomenon
• Testing the Completeness of the SDSS Colour Selection for Ultramassive, Slowly Spinning Black Holes
• Milky Way dust extinction measured with QSOs
• The Properties of Type Ia Supernova Host Galaxies from the Sloan Digital Sky Survey
• Further Evidence that the Redshifts of AGN Galaxies May Contain Intrinsic Components
• Optical Selection of Faint AGN in the COSMOS Field
• A Stellar Population Synthesis Model for the Study of Ultraviolet Star Counts of the Galaxy
• Catalog of Candidates for Quasars at 3 < z < 5.5 Selected among X-Ray Sources from the 3XMM-DR4 Survey of the XMM-Newton Observatory
• A candidate of binary black hole system in AGN with broad Balmer emission lines having quite different line widths
• Seyfert 1 Composite Spectrum using SDSS Legacy Survey Data
• A study of the 15 micron quasars in the ELAIS N1 and N2 fields
• Capability of Quasar Selection by Combining the SCUSS and SDSS Observations
• Quasars as Standard Candles V. Evaluation of a $\le$ 0.06 dex intrinsic dispersion in the LX-LUV relation
• Common Proper Motion Wide White Dwarf Binaries Selected From The Sloan Digital Sky Survey
• A quasar companion to the puzzling quasar SDSS J0927+2943
• Sample of Cataclysmic Variables from 400d X-ray Survey
• The Space Density of Intermediate Redshift, Extremely Compact, Massive Starburst Galaxies
• Tuning target selection algorithms to improve galaxy redshift estimates
• A Systematic Analysis of Stellar Populations in the Host Galaxies of SDSS Type I QSOs
• The Southern 2MASS AGN Survey: spectroscopic follow-up with 6dF
• Active galactic nuclei catalog from the AKARI NEP Wide field
• DESIVAST: A Catalog of Low-Redshift Voids using Data from the DESI DR1 Bright Galaxy Survey
• Composite reverberation mapping
• Reddening and the Shape of the Variable Component of the Continua of Active Galactic Nuclei From the Optical to the Far Ultraviolet. I
• Seeking the Epoch of Maximum Luminosity for Dusty Quasars
• Modelling Grain Rotational Disruption by Radiative Torques and Extinction of Active Galactic Nuclei
• SDSS Pre-Burst Observations of Recent Gamma-Ray Burst Fields
• Identifying type II quasars at intermediate redshift with few-shot learning photometric classification
• The optical luminosity function of LOFAR radio-selected quasars at $1.4\le z\le 5.0$ in the NDWFS-Boötes field
• Selection Effects in the SDSS Quasar Sample: The Filter Gap Footprint
• Deep CFHT Y-band Imaging of VVDS-F22 Field: II. Quasar Selection and Quasar Luminosity Function
• A Precision Multi-Band Two-Epoch Photometric Catalog of 44 Million Sources in the Northern Sky from Combination of the USNO-B and Sloan Digital Sky Survey Catalogs
• Spectral Identification of the u-band Variable Sources in Two LAMOST fields
• Powerful Radio Emission From Low-mass Supermassive Black Holes Favors Disk-like Bulges
• The probabilistic random forest applied to the QUBRICS survey: improving the selection of high-redshift quasars with synthetic data
• Probing the Wind Component of Radio Emission in Luminous High-Redshift Quasars
• The host galaxy of low-luminosity compact sources
• Properties of spectrally-defined red QSOs at z = 0.3-1.2
• Constraints on the optical polarization source in the luminous non-blazar quasar 3C 323.1 (PG 1545+210) from the photometric and polarimetric variability
• Approximate Inference for Constructing Astronomical Catalogs from Images
• Multi-phase gas properties of extremely strong intervening DLAs towards quasars
• Morpho-Photometric Classification of KiDS DR5 Sources Based on Neural Networks: A Comprehensive Star-Quasar-Galaxy Catalog
• The 2.4 $\mu$m Galaxy Luminosity Function as Measured Using WISE. III. Measurement Results
• Discovery of six high-redshift quasars with the Lijiang 2.4m telescope and the Multiple Mirror Telescope
• A cosmological distance measure using radio-loud quasars
• Serendipitous discovery of a projected pair of QSOs separated by 4.5 arcsec on the sky
• Deep CFHT Y-band imaging of VVDS-F22 field: I. data products and photometric redshifts
• Discovering bright quasars at intermediate redshifts based on the optical/near-IR colors
• Objective Subclass Determination of Sloan Digital Sky Survey Unknown Spectral Objects
• Properties of Stars in the Subaru Deep Field
• Photometric Identification of Objects from Galaxy Evolution Explorer Survey and Sloan Digital Sky Survey
• The Diversity of Environments Around Luminous Quasars at Redshift $z\sim 6$
• Extreme Galaxy-scale Outflows Are Frequent among Luminous Early Quasars
• Properties of Near-Infrared Selected AGN Candidates with 2MASS/ROSAT Catalogues
• Application of USNO-B1.0 towards selecting objects with displaced blue and red components
• The distant red galaxy neighbour population of 1 < z < 2 QSOs and optically obscured sources
• Effects of Smoothing Functions in Cosmological Counts-in-Cells Analysis
• Optical selection of quasars: SDSS and LSST
• The Feasibility and Flexibility of Selecting Quasars by Variability Using Ensemble Machine Learning Algorithms
• Decadal Variability Survey in MACSJ1149
• Quasar catalogue for the astrometric calibration of the forthcoming ILMT survey
• Mid-infrared Variability-based AGN Selection using the Multi-epoch Photometric Data from WISE
• The Sloan Digital Sky Survey DR7 Spectroscopic M Dwarf Catalog II: Statistical Parallax Analysis
• Discovery of a New Blue Quasar: SDSS J022218.03-062511.1
• The 2.4 $\mu$m Galaxy Luminosity Function as Measured Using WISE. II. Sample Selection
• Comparison of symbolic regression algorithms in Star/galaxy/quasar separation
• Zeta-Payne: a fully automated spectrum analysis algorithm for the Milky Way Mapper program of the SDSS-V survey
• Quasars physical properties study based on the medium-band photometric survey
• Extreme variability quasars from the Sloan Digital Sky Survey and the Dark Energy Survey
• AGILE: an end-to-end Rubin-LSST simulation of AGNs, galaxies, and stars I. Software description and first data release
• Searching for Magnetic White Dwarfs in LAMOST DR10
• The miniJPAS survey quasar selection I: Mock catalogues for classification
• Re-Identification of the `Enigmatic' X-ray Source 1RXS J114003.0+124112
• Spectroscopic confirmation of dual and offset quasars from the Subaru HSC-SSP program
• Exploring the Variable Sky with the Sloan Digital Sky Survey
• Using the large scale quasar clustering to constrain flat quintessential universes