1,385 datasets found

The goal to this work is to observe a first set of 70 extragalactic sources at optical wavelengths that could achieve the link with the ICRF. Variations in the light curves of...

We present four years of photometric observations of the doubly imaged quasar UM673, carried out in three filters (VRi) with the Danish 1.54m telescope at the La Silla...

We present an absorption-selected survey of CaII and NaI features located in the halo of the Milky Way using QSO absorption spectroscopy. We made use of the ESO data archive and...

Large spectroscopic surveys have discovered very peculiar and hitherto unknown types of active galactic nuclei (AGN). Such rare objects may hold clues to the accretion history...

We present simultaneous Planck, Swift, Fermi, and ground-based data for 105 blazars belonging to three samples with flux limits in the soft X-ray, hard X-ray, and {gamma}-ray...

From a principal component analysis (PCA) of 78 z~3 high-quality quasar spectra in the SDSS-DR7 we derive the principal components that characterize the QSO continuum over the...

While analyzing decades of very long baseline interferometry (VLBI) data, we detected the secular aberration drift of the extragalactic radio source proper motions caused by the...

We present VRi photometric observations of the quadruply imaged quasar HE0435-1223, carried out with the Danish 1.54m telescope at the La Silla Observatory. Our aim was to...

We have searched for microlensing variability in the light curves of five gravitationally lensed quasars with well-determined time delays: SBS 1520+530, FBQ 0951+2635, RX...

The files table1.dat and table2.dat contain light curves of the double quasar SBS1520+530 obtained at Maidanak observatory from April 2003 to August 2004. table1.dat contains...

We present a catalogue of 286 X-ray sources with their optical identification taken from the XMDS survey (using the XMM-Newton EPIC instrument). This first version is limited to...

We determined the basic parameters, such as the central black hole mass (M), the boosting factor (or Doppler factor) ({delta}) the propagation angle ({Phi}) and the distance...

We use the first data release of the 2-degree Field quasar survey (Cat. ) to investigate the effect of gravitational magnification by foreground absorbing systems on background...

We discuss the "angular size-redshift" relation for compact radio sources distributed over a wide range of redshifts 0.011<=z<=4.72. Our study is based on a sample of 330...

The table contains optical polarization data for a sample of 170 moderate to high-redshift quasars

We have compiled a sample of all quasars with measured radio emission from the Veron-Cetty - Veron catalogue (1993, VV93 ) detected by ROSAT in the ALL-SKY SURVEY (RASS, Voges...

The simple unification scheme of powerful radio galaxies and quasars, based entirely on the orientation dependent effects, has been confronted with the observed radio structures...

A gravitational lens (GL)-search program, initiated in 1990 at the Nordic Optcal Telescope (NOT), has revealed several possible GL-candidates among a sample of 168 quasars...

We describe a survey for variable QSOs carried out for 15 years with the UK Schmidt telescope, using IIIaJ plates exposed behind a Schott GG395 filter. Objects brighter than...

Ultraviolet observations of the high-redshift quasat HS 1700+6416 were obtained with the Faint Object Spectrograph (FOS) onboard the Hubble Space Telescope (HST) in the range...