The experimental study of laser beam propagation in turbulence is relevant to fields such as adaptive optics and optical communications. Turbulence sensing for astronomical purposes requires a convergent laser beam adequately focused on the sodium mesospheric layer. Free Optical communications ground-to-satellite usually are based on divergent

The observed masses of the most massive stars do not surpass about 150 Msolar. This may either be a fundamental upper mass limit which is defined by the physics of massive stars and/or their formation, or it may simply reflect the increasing sparsity of such very massive stars, so that the observation of even higher mass stars becomes unlikely in

As a result of an error in processing proof corrections, the feature labels in the bottom panel of Figure 1 are incorrect. The correct Figure 1 is given here. The press sincerely regrets this error.

2S 1711-339: In ATEL #233 the absorbed X-ray flux of 2S 1711-339 was incorrectly given as 2e-15 ergs cm-2 s-1 (0.3-7.0 keV). The correct value obtained by using a blackbody model with kT = 0.24 +/- 0.03 keV or a neutron-star hydrogen-atmosphere model with kT = 0.07 +/- 0.03 keV is 1.0e-14 ergs cm-2 s-1 (0.5-10.0 keV). This flux is a factor of 10

Major Atmospheric Gamma Imaging Cherenkov telescope is starting its operations with a set of engineering runs to tune the telescope subsystem elements to be ready for the first physics campaign. Many technical improvements have been developed and implemented in several elements of the telescope to reach the lowest energy threshold ever obtained by

We have gathered and analysed a timeseries of 1493 high-quality multicolour Geneva photometric data of the B3V β Cep star HD 129929. The dataset has a time base of 21.2 years. The occurrence of a beating phenomenon is evident from the data. We find evidence for the presence of at least six frequencies, among which we see components of two frequency