Experimental Gamma-Ray Astronomy

Our knowledge of the γ-ray sky has dramatically changed due to the advent of the new ground-based Imaging Atmospheric Cherenkov Telescopes (H.E.S.S., MAGIC and VEPJTAS) and the satellite-borne instruments (AGILE and Fermi). These facilities boosted the number of γ-ray sources by one order of magnitude in the last 6 years, providing us with about 2000 sources detected above 100 MeV (from space) and about 100 sources detected above 100 GeV (from the ground). The combination of this large leap in experimental capabilities together with the fact that the Universe is still quite unexplored at these extreme energies is evidence of a large scientific discovery potential that will surely make the decade 2010–2020 a golden age for γ-ray astronomy. In this manuscript I provide a subjective review of some of the most exciting observations from this rapidly evolving field during the last two years.