The last years saw numerous detections of substructure in the Galactic halo, largely due to wide area surveys like the Sloan Digital Sky Survey (SDSS) or the...
SDSS J0909+4449: A large-separation strongly lensed quasar at z ˜ 2.8 with three images
We report the discovery of SDSS J0909+4449, an exceptional system consisting of a quasar at z = 2.788 strongly lensed by a group of galaxies at z ˜ 0.9 into...
Search for very high energy gamma-rays from the z = 0.896 quasar 4C +55.17 with the MAGIC telescopes
The bright gamma-ray quasar 4C +55.17 is a distant source (z = 0.896) with a hard spectrum at GeV energies as observed by the Large Area Telescope (LAT) on...
Serendipitous Discovery of a Projected Pair of QSOs Separated by 4.5 arcsec on the Sky
We present the serendipitous discovery of a projected pair of quasi-stellar objects (QSOs) with an angular separation of Δθ = 4.50 arcsec. The redshifts of the...
SHARDS: A Global View of the Star Formation Activity at z ~ 0.84 and z ~ 1.23
In this paper, we present a comprehensive analysis of star-forming galaxies (SFGs) at intermediate redshifts (z ∼ 1). We combine the ultra-deep optical spectro...
Short time-scale fluctuations in the difference light curves of QSO 0957+561A,B: microlensing or noise?
From optical R-band data of the double quasar QSO 0957+561A,B, we made two new difference light curves (with an overlap of about 330d between the time-shifted...
Simultaneous UBVRI photopolarimetric observations of blazars. II
Results are presented from simultaneous UBVRI photopolarimetric observations of eight blazars at the 2.56-m Nordic Optical Telescope during winter 1991. In 3C...
Size of the Accretion Disk in the Graviationally Lensed Quasar SDSS J1004+4112 from the Statistics of Microlensing Magnifications
We present eight monitoring seasons of the four brightest images of the gravitational lens SDSS J1004+4112 observed between 2003 December and 2010 October...
Sloan Digital Sky Survey Quasars in the Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE) ELAIS N1 Field: Properties and Spectral Energy Distributions
We present a mid-infrared (MIR) analysis of 35 quasars with spectroscopic redshifts selected from the Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE)...