348 datasets found

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 have collected a large amount of multifrequency data for objects in the Metsahovi Radio Observatory BL Lacertae sample and computed their spectral energy distributions (SED)...

2482 BVRI photometric data on eight red blazars taken from 3 Observatories in the period 2003 September - 2004 February are presented. A table is given, containing the source...

We address the topic of the intra-night optical variability of the BL Lac object S5 0716+714. To this purpose a long-term observational campaign was carried out, from 1996 to...

We present EVN observations of seven BL Lac objects selected from the RGB sample. To investigate the intrinsic radiation property of BL Lac objects, we estimated the Doppler...

Spectral variability is the main tool for constraining emission models of BL Lac objects. By means of systematic observations of the BL Lac prototype PKS 2155-304 in the...

The multi-frequency sedentary survey is a flux-limited, statistically well-defined sample of highly X-ray dominated (i.e., with a very high X-ray to radio flux ratio) BL...

Although Blazars are a small fraction of the overall AGN population they are expected to be the dominant population of extragalactic sources in the hard X-ray and gamma-ray...

We present a new catalogue of blazars based on multifrequency surveys and on an extensive review of the literature. Blazars are classified as BL Lacertae objects, as flat...

The European space astrometry mission Gaia will construct a dense optical QSO-based celestial reference frame. For consistency between optical and radio positions, it will be...

We present the results of a study on the blazar content in the 15-150keV map of the entire sky obtained analyzing 39 months of data collected by the BAT telescope aboard the...

The European space astrometry mission Gaia, to be launched by 2012, will construct a dense optical QSO-based celestial reference frame which will need to be linked to the...

195 polarimetric measurements of 182 BL Lac candidates from the SDSS taken with 3 different telescopes are presented. For each candidate the J2000 coordinates, its redshift,...

The long-term optical light curve of PKS 2155-304 is assembled from archival data as well as from so-far unpublished observations mostly carried out with the ROTSE-III and the...

Observations of the {gamma}-ray sky with Fermi led to significant advances towards understanding blazars, the most extreme class of active galactic nuclei. A large fraction of...

Multiwavelength (MWL) observations of the blazar PKS 2155-304 during two weeks in July and August 2006, the period when two exceptional flares at very high energies (VHE,...

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...

1RXS J101015.9-311909 is a galaxy located at a redshift of z=0.14 hosting an active nucleus (called AGN) belonging to the class of bright BL Lac objects. Observations at high...

High-resolution radio observations are ideal for constraining the value of physical parameters in the inner regions of active-galactic-nucleus jets and complement results on...

Combining measurements taken using the Wilkinson Microwave Anisotropy Probe (WMAP) from 2001 to 2008 with measurements taken using Planck from 2009 to 2010, we investigate the...