The Perseus galaxy cluster was observed by the MAGIC Cherenkov telescope for a total effective time of 24.4 hr during 2008 November and December. The resulting upper limits on the γ-ray emission above 100 GeV are in the range of 4.6-7.5 × 10-12 cm-2 s-1 for spectral indices from -1.5 to -2.5, thereby constraining the emission produced by cosmic

Context. The process that heats the solar chromosphere is a difficult target for observational studies because the assumption of local thermal equilibrium (LTE) is not valid in the upper solar atmosphere, which complicates the analysis of spectra. Aims: We investigate the linear correlation coefficient between the intensities at different

In order to know the formation epoch of the oldest elliptical galaxies as a function of mass and observed redshift, a statistical analysis of 333 extremely red objects (EROs) classified as old galaxies (OGs) at 0.8

Light curves of four eclipsing cataclysmic variable stars and five non-eclipsing cataclysmic variables are presented. The data were obtained using the ESO/NTT/EFOSC2 and ING/WHT/ACAM telescopes and instruments. For the NTT a Tyson B filter was used (ESO filter #724) whereas for the WHT a Johnson V filter was used. (14 data files).

SW Sextantis stars are fundamental to understanding how cataclysmic variables evolve. Their maverick behavior and unexplained accumulation in the orbital period range 3-4 h, about to enter the ``period gap'' where mass transfer is predicted to cease until a period of 2 h is reached, challenge the current evolution theory. To characterize these

The frontiers of high time resolution Astrophysics are rapidly expanding, moving from the traditional X-ray Astronomy to more and more wavelengths. The study of X-ray variability in X-ray binaries has represented - and still is - one of the most powerful tools to study the accretion flow in the vicinity of compact objects. Recent optical