The field of astroparticle physics is currently develo** rapidly, since new experiments
challenge our understanding of processes that have been investigated. Three messengers …

Very high-energy gamma-ray astronomy has emerged as an exciting and vital field. In the
last seven years, major discoveries have been made by experiments in space and on the …

Gamma ray astronomy, the branch of high energy astrophysics that studies the sky in
energetic γ-ray photons, is destined to play a crucial role in the exploration of nonthermal …

Following the detection of strong TeV γ-ray flares from the BL Lac object 1ES 1959+ 650
with the Whipple 10 m Cerenkov telescope on 2002 May 16 and 17, we performed intensive …

We performed an observational program with the X-ray satellite BeppoSAX, to study objects
with extreme synchrotron peak frequencies (keV). Of the seven sources observed, five …

Recent advances in ground-based gamma ray astronomy have led to the discovery of more
than 70 sources of very high energy (E γ⩾ 100 GeV) gamma rays, falling into a number of …

We have used data from a TeV γ-ray flare associated with the active galaxy Markarian 421 to
place bounds on the possible energy dependence of the speed of light in the context of an …

The close X-ray–selected BL Lac PKS 2155-304 has been observed using the University of
Durham Mark 6 very high energy (VHE) gamma-ray telescope during 1996 …

ABSTRACT BL Lac objects are the best candidates to study the jet properties since their
spectral energy distributions (SEDs) are less contaminated by the emission from the …

We present the results of a multiwavelength campaign for Mrk 501 performed in 1996 March
with ASCA, EGRET, Whipple, and optical telescopes. The X-ray flux observed with ASCA …