The BL Lacertae object AO 0235+16 is well known for its extreme optical and radio variability. New optical and radio data have been collected in the last four...

The study of gamma-ray blazars is usually hindered due to the lack of information on their redshifts and on their low-energy photon fields. This information is...

The study of gamma-ray blazars is usually hindered due to the lack of information on their redshifts and on their low-energy photon fields. This information is...

The emission from the relativistic jets in blazars usually outshines their host galaxies, challenging the determination of their distances and the...

We present optical spectrophotometric observations for 50 blazars obtained in 13 different campaigns over a 7 year period. The spectral flux distribution is...

We present optical spectroscopy secured at the 10 m Gran Telescopio Canarias of the counterparts of 20 extragalactic γ-ray sources detected by the Fermi...

We report on optical spectroscopy obtained at the 10.4 m Gran Telescopio Canarias of 28 Fermi γ-ray sources that completes the study of a sample of 60 targets...

We investigate the spectroscopic optical properties of gamma-ray sources detected with high significance above 50 GeV in the Third Catalog of Hard Fermi-LAT...

Context. Blazars are the most numerous class of high-energy (HE; E ∼ 50 MeV−100 GeV) and very high-energy (VHE; E ∼ 100 GeV−10 TeV) gamma-ray emitters...