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A large quasar group (LQG) of particularly large size and high membership has been identified in the DR7QSO catalogue of the Sloan Digital Sky Survey. It has characteristic size (volume 1/3) ∼500 Mpc (proper size, present epoch), longest dimension ∼1240 Mpc, membership of 73 quasars and mean redshift ¯ z = 1.27. In terms of both size and membership, it is(More)
The Chile-UK quasar survey, a new-generation 140 deg 2 UVX survey to B = 20, is now ∼ 25% complete. The catalogue currently contains 319 quasars and 93 emission line galaxies. Using the minimal-spanning tree method, we have independently confirmed the ∼ 200 h −1 Mpc group of quasars at z ≃ 1.3 discovered by Clowes & Campusano (1991). We have discovered a(More)
We are looking at quasar environment in the context of large-scale structure (LSS) — a new approach, giving a more informed interpretation of quasar-galaxy correlations. This paper presents our first results for a sample of z ∼ 0.3 quasars. We are using Voronoi tessellation applied in colour (B J −R) slices for the detection of galaxy clusters and the(More)
We report the finding of two large-scale structures of galaxies in a 40 × 35 arcmin 2 field embedded in a 25 deg 2 area where two 100 h −1 Mpc-scale structures of quasars and Mg  absorbers at z ≃ 0.8 and z ≃ 1.2 have been previously detected. Using deep optical (V-and I-band) imaging, we are able to select high-redshift (0.5 ∼ < z ∼ < 1.3) early-type(More)
A new assessment of the completeness of quasar surveys: implications for the luminosity function Received ; accepted – 2 – ABSTRACT We apply a simple statistical method (Derenzo & Hildebrand 1969) to estimating the completeness of quasar surveys. It requires that an area has been covered by two or more, preferably different, selection techniques. We use(More)