The Cosmic Lens All-Sky Survey - I. Source selection and observations

By Steven T. Myers, Steven T. Myers, N. Jackson, I. Browne, A. Bruyn, T. Pearson, A. Readhead, P. Wilkinson, A. Biggs, R. Blandford and 9 more. 2002

305 citations recorded by the source corpus.

The Cosmic Lens All-Sky Survey (CLASS) is an international collaborative program which has obtained high-resolution radio images of over 10000 flat-spectrum radio sources in order to create the largest and best studied statistical sample of radioloud gravitationally lensed systems. With this survey, combined with detailed studies of the lenses found therein, constraints can be placed on the expansion rate, matter density, and dark energy (e.g. cosmological constant, quintessence) content of the Universe that are complementary to and independent of those obtained through other methods. CLASS is aimed at identifying lenses where multiple images are formed from compact flat-spectrum radio sources, which should be easily identifiable in the radio maps. Because CLASS is radio-based, dust obscuration in lensing galaxies is not a factor, and the relative insensitivity of the instrument to environmental conditions (e.g. weather, “seeing”) leads to nearly uniform sensitivity and resolution over the entire survey. In four observing “seasons” from 1994–1999, CLASS has observed 13783 radio sources with the VLA at 8.4 GHz in its largest “A” configuration (0. ′′ 2 resolution). When combined with the JVAS survey, the CLASS sample contains over 16,000 images. A complete sample of 11685 sources was observed, selected to have a flux density of at least 30 mJy in the GB6 catalogue at 4.85 GHz (spanning the declination range 0 ◦ 6 � 6 75 ◦ and |b| > 10 ◦ , excluding the galactic plane) and a spectral index � > 0.5 between the NVSS at 1.4 GHz and the GB6. A typical 30second CLASS snapshot reached an rms noise level of 0.4 mJy. So far, CLASS has found 16 new gravitational lens systems, and the JVAS/CLASS survey contains a total of 22 lenses. The follow-up of a small number of candidates using the VLA, MERLIN, the VLBA, and optical telescopes is still underway. In this paper, we present a summary of the CLASS observations, the JVAS/CLASS sample, and statistics on sub-samples of the survey. A companion paper presents the lens candidate selection and in a third paper the implications for cosmology are discussed. The source catalogues from the JVAS/CLASS project described in this paper are available from http://www.jb.man.ac.uk/research/gravlens/ .

Subfields: Astronomy and Astrophysics

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Citations in the corpus

CGRaBS: An All-Sky Survey of Gamma-Ray Blazar Candidates (2007, background): “Healey et al. (2007) have recently developed such a catalog, CRATES, which extended results of the Cosmic Lens All-Sky Survey (CLASS; Myers et al. 2003) to obtain 8.4 GHz observations of all jbj> 10 objects brighter than 65 mJy at 4.8 GHz with spectral indices > 0:5 (where S / ).”
THE FIRST CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE (2010, background): “The prefix “CLASS” refers to sources from the Cosmic Lens All-Sky Survey (Myers et al. 2003; Browne et al. 2003).”
CRATES: An All-Sky Survey of Flat-Spectrum Radio Sources (2007, methodology): “Our survey is designed as an extension of the largest highfrequency interferometric survey currently available, the Cosmic Lens All-Sky Survey (CLASS; Myers et al. 2003).”
Strong-lensing optical depths in a ΛCDM universe – II. The influence of the stellar mass in galaxies (2007, background): “This includes the inner few arcseconds of most lenses, regions which dominate many surveys for strong lensing (Myers et al. 2003; Oguri et al. 2006; Bolton et al. 2006; Willis et al. 2006; Cabanac et al. 2007).”
DISSECTING THE GRAVITATIONAL LENS B1608+656. II. PRECISION MEASUREMENTS OF THE HUBBLE CONSTANT, SPATIAL CURVATURE, AND THE DARK ENERGY EQUATION OF STATE (2009, background): “The quadruple-image gravitational lens B1608+656 was discovered in the Cosmic Lens All-Sky Survey (CLASS) (Myers et al. 1995; Browne et al. 2003; Myers et al. 2003).”
The Supernova Legacy Survey: Measurement of Omega_M, Omega_Lambda,and w from the First Year Data Set (2005, background): “Multiple images of distant radio sources have been systematically searched by the CLASS survey (Myers et al. 2003) and have proved to be rare: the occurrence of multiple images sep- arated by more than 0.3′′ and with flux ratio below 10:1 was found to be of 1 out of 690 with 1.44 secondary image on…”
The Sloan Lens ACS Survey. VI. Discovery and Analysis of a Double Einstein Ring (2008, background): “…known galaxy-scale gravitational lens systems has increased well beyond a hundred as a result of a number of dedicated efforts exploiting a variety of techniques (e.g. Warren et al. 1996; Ratnatunga et al. 1999; Kochanek et al. 1999; Myers et al. 2003; Bolton et al. 2004; Cabanac et al. 2007).”
Astrophysical and cosmological information from large-scale submillimetre surveys of extragalactic sources (2007, methodology): “For comparison, the radio Cosmic Lens All-Sky Survey (CLASS; Browne et al. 2003; Myers et al. 2003), that has been the basis for most analyses of lens statistics, has yielded a sample of 22 gravitational lens systems.”
Gravitationally lensed quasars and supernovae in future wide-field optical imaging surveys (2010, background): “…hundred strong lens systems produced by massive galaxies have been discovered to date, with quasars (e.g. Inada et al. 2008), radio sources (e.g. Browne et al. 2003; Myers et al. 2003) and galaxies (e.g. Cabanac et al. 2007; Bolton et al. 2008; Faure et al. 2008) appearing as source populations.”
Gravitational Lens Time Delays: A Statistical Assessment of Lens Model Dependences and Implications for the Global Hubble Constant (2006, methodology): “We adopt q ¼ 2:1, which is relevant for lenses identified by Cosmic Lens All-Sky Survey (CLASS) (Myers et al. 2003).”
Roma-BZCAT: A multifrequency catalogue of Blazars (2008, background): “…the CRATES (Combined Radio All-Sky Targeted Eight GHz Sources) catalogue (Healey et al. 2007), which extended the CLASS (Cosmic Lens All-Sky Survey, Myers et al. 2003) to obtain observations at 8.4 GHz of flat spectrum sources with |b| > 10◦ and brighter than 65 mJy at 4.8 GHz, with the exclusion…”
The VLBA Imaging and Polarimetry Survey at 5 GHz (2006, methodology): “To this end, the Cosmic Lens All-Sky Survey (CLASS;Myers et al. 2003) as the parent sample was chosen.”
GRAVITATIONAL LENS MODELS BASED ON SUBMILLIMETER ARRAY IMAGING OF HERSCHEL-SELECTED STRONGLY LENSED SUB-MILLIMETER GALAXIES AT z > 1.5 (2013, methodology): “…in the radio with the Jodrell Bank Very Large Array gravitational lens survey (JVAS; King & Browne 1996) and the Cosmic Lens All-Sky Survey (CLASS; Myers et al. 2003) or on Hubble Space Telescope (HST) follow-up of known strong lenses as part of the Center for Astrophysics Arizona Space Telescope…”
H0LiCOW – I. H0 Lenses in COSMOGRAIL's wellspring: program overview (2016, background): “The lens system was discovered in the Cosmic Lens All-Sky Survey (CLASS; Myers et al. 1995; Browne et al. 2003; Myers et al. 2003).”
THE THIRD CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE (2015, background): “…(Murphy et al. 2010), VCS (Kovalev et al. 2007), CRATES (Healey et al. 2007), PMN-CA (Wright et al. 1996), CRATESGaps (Healey et al. 2007), or CLASS (Myers et al. 2003) source lists, that indicates a flat radio spectrum, and shows a typical two-humped, blazar-like SED; and (c) a source included…”
The Karl G. Jansky Very Large Array Sky Survey (VLASS). Science Case and Survey Design (2019, methodology): “A crude estimation based on the the statistics of the Cosmic Lens All-Sky survey (CLASS; Myers et al. 2003) suggests that the VLASS has the potential to identify ∼ 10 new wide separation (> 2.”