Related papers: Optical spectroscopy of blazars for the Cherenkov …

The VERITAS array of imaging atmospheric Cherenkov telescopes has collected nearly 6000 hours of observations of active galactic nuclei (AGNs). It has detected 39 very-high-energy (VHE, >100 GeV) AGNs at redshifts up to z = 0.9, of which 24…

The Fermi/LAT telescope is an efficient blazar-detector in the MeV/GeV range. More than 1100 (900) blazars detected above 100 MeV (10 GeV) are clearly associated to BL Lacertae or Flat Spectrum Radio Quasar objects in the Fermi/LAT 3FGL…

BL Lacertae objects (BL Lacs) represent a large fraction (22\%) of gamma-ray sources in the Third Fermi Large Area Telescope catalog (3FGL). Nearly half of the BL Lac population remains without a redshift because of their featureless…

We present the results of nine years of the blazar observing programme at the RATAN-600 radio telescope (2005-2014). The data were obtained at six frequency bands (1.1, 2.3, 4.8, 7.7, 11.2, 21.7 GHz) for 290 blazars, mostly BL Lacs. In…

We present the observational results of multi-colour optical monitoring of eight red blazars from 2003 September to 2004 February. The aim of our monitoring is to investigate the spectral variability as well as the flux variations at short…

In this first systematic attempt to characterise the intranight optical variability (INOV) of TeV detected blazars, we have monitored a well defined set of 9 TeV blazars on total 26 nights during 2004-2010. In this R (or V)-band monitoring…

Large Array of imaging atmospheric Cherenkov Telescope (LACT) is an array of 32 Cherenkov telescopes with 6-meter diameter mirrors to be constructed at the LHAASO site. In this work, we present a study on the layout optimization and…

The extragalactic gamma-ray sky is dominated by the emission arising from blazars, one of the most peculiar classes of radio-loud active galaxies. Since the launch of Fermi several methods were developed to search for blazars as potential…

We discuss the prospects for the detection of gamma-ray bursts (GRBs) by the Cherenkov Telescope Array (CTA), the next generation, ground-based facility of imaging atmospheric Cherenkov telescopes (IACTs) operating above a few tens of GeV.…

PKS 2155-304 is a well-known high-frequency peaked BL Lac (HBL) at redshift z=0.116, which has been extensively studied across the electromagnetic spectrum due to its rapid and large-amplitude variability. Several violent outbursts in…

Extreme high-frequency peaked BL Lac objects (EHBLs) are blazars which exhibit extremely energetic synchrotron emission. They also feature non-thermal gamma-ray emission whose peak lies in the very high-energy (VHE, E > 100 GeV) range, and…

We present a study of high-cadence, high-precision, optical light curves from the TESS satellite of 67 blazars in the southern sky. We provide descriptive flux statistics, power spectral density model parameters, and characteristic…

Blazars and in particular the subclass of high synchrotron peaked Active Galactic Nuclei are among the main targets for the present generation of Imaging Atmospheric Cherenkov Telescopes (IACTs) and will remain of great importance for very…

Blazars are active galactic nuclei (AGN) with a relativistic jet oriented toward the observer. This jet is composed of accelerated particles which can display emission over the entire electromagnetic spectrum. Spectral variability has been…

Many blazars detected by the Fermi satellite, observed spectroscopically in the optical, are line-less, and have been classified as BL Lac objects. Optical-UV photometry of nearly one hundred of them allowed to determine the redshift for a…

We introduce a new method to determine the redshift of unknown-redshift BL Lac Objects. The method relies on simultaneous multi-wavelength (MWL) observations of BL Lac objects in optical, X-ray, HE (E>100 MeV) gamma-rays and VHE (E>100…

The synergy between the Fermi-LAT and ground-based Cherenkov telescope arrays gives us the opportunity for the first time to characterize the high energy emission (100 MeV - 10 TeV) from more than 30 blazars. In this study we performed a…

We used the DEIMOS spectrograph on the Keck II Telescope to obtain spectra of galaxies in the fields of five distant, rich galaxy clusters over the redshift range 0.5 < z < 0.9 in a search for luminous, compact, blue galaxies (LCBGs).…

We report the main results of our six year long intensive optical monitoring on blazars ON 231 (W Com), BL Lac, and 3C 273. Intensive optical monitoring is an indispensable tool to obtain well sampled light curves and thus to understand the…

We analyse a group of radio sources, a subset of the 200 mJy sample, all of which have core-jet radio structures measured with VLBI and have flat spectra stretching from the radio to the millimetre/sub-millimetre band. Thus the objects have…