In ATel #1815 we erroneously associated the globular cluster M31GC J004234+405709 (Bol 117) with object s1-1 from Williams et al. (2006, ApJ 643, 356). Bol 117 is not associated with any previously catalogued X-ray source, so the Chandra observation we report on in ATel #1815 is the first recorded detection of X-ray activity from Bol 117. The

The microquasar V404 Cygni underwent a series of outbursts in 2015, June 15-31, during which its flux in hard X-rays (20-40 keV) reached about 40 times the Crab nebula flux. Because of the exceptional interest of the flaring activity from this source, observations at several wavelengths were conducted. The MAGIC telescopes, triggered by the

MAGIC is built to perform observations of prompt and early afterglow emission from Gamma-Ray Bursts (GRBs) above 25 GeV. The instrument is designed to have the lowest possible energy threshold among the ground based γ-ray detectors and the fastest reaction time to alerts distributed over the GRB Coordinates Network (GCN). The MAGIC-I telescope

Aims: We investigate the photometric modulation induced by magnetic activity cycles and study the relationship between rotation period and activity cycle(s) in late-type (FGKM) stars. Methods: We analysed light curves, spanning up to nine years, of 125 nearby stars provided by the All Sky Automated Survey (ASAS). The sample is mainly composed of

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Gonçalves et al. (1996) showed the relevance of Alfvén heating in order to establish the stability of quasar broad-line region clouds in the intercloud medium due to thermal instability. Although, photoionization by the continuum radiation from the central source is the most important mechanism to heat and ionize the broad-line region, Alfvenic