The active galactic nucleus PG 1553+113 was observed by the MAGIC telescope in July 2006 during a multiwavelength campaign, in which telescopes in the optical, X-ray, and very high energies participated. Although the MAGIC data were affected by strong atmospheric absorption (calima), they were analyzed after applying a correction. In 8.5 h, a

The physics of blazar flares is still not well understood. Currently favored emission models include electron inverse Compton (IC) scattering of low-energy synchrotron photons from within the jet or photons generated outside the jet, emission produced by the proton initiated cascades or synchrotron emission of extremely high-energy protons or muons

The Cherenkov light flashes produced by extensive air showers are very short in time. A high bandwidth and fast digitizing readout, therefore, can minimize the influence of the background from the light of the night sky, and improve the performance in Cherenkov telescopes. The time structure of the Cherenkov image can further be used in single-dish

We present an algorithm (MEAD, for `Mapping Extinction Against Distance') which will determine intrinsic (r' - i') colour, extinction, and distance for early-A to K4 stars extracted from the IPHAS r'/i'/Hα photometric data base. These data can be binned up to map extinction in three dimensions across the northern Galactic plane. The large size of

Context: ω Centauri is the most well studied Galactic Globular Cluster because of its numerous puzzling features: significant dispersion in metallicity, multiple populations, triple main-sequence, horizontal branch morphology, He-rich population(s), and extended star-formation history. Intensive spectroscopic follow-up observing campaigns targeting

We present new global mass functions for a large number of clusters from the ACS Survey of Galactic Globular Clusters and find that the majority of the mass functions follow power-law behavior from the main sequence turnoff (at approximately 0.7 solar masses) down to our completeness limit (at approximately 0.3 solar masses). Comparing the mass