We report results from a re-analysis of the BeppoSAX observation of Coma and from the analysis of a second, yet unpublished observation of the same object. From our re-analysis of the first observation we find that the statistical evidence for a hard tail is about 2σ. From the analysis of the second observation which, thanks to the lower background and the longer exposure time, is characterized...

The objective of this article is to build up a general theory of geometrical optics for spinning light rays in an inhomogeneous and anisotropic medium modeled on a Finsler manifold. The prerequisites of local Finsler geometry are reviewed together with the main properties of the Cartan connection used in this work. Then, the principles of Finslerian spinoptics are formulated on the grounds of p...

The method devised by Lewis et al. (1993) for calculating the light curve of a microlensed point source is expanded to two dimensions to enable the calculation of light curves of extended sources. This method is significantly faster than the ray shooting method that has been used in the past. The increased efficiency is used to obtain much higher resolution light curves over increased time scal...

We study Doppler effects in curved space-time, i.e. the frequency shifts induced on electromagnetic signals propagating in the gravitational field. In particular, we focus on the frequency shift due to the bending of light rays in weak gravitational fields. We consider, using the PPN formalism, the gravitational field of an axially symmetric distribution of mass. The zeroth order, i.e. the sphe...

The shifting of spectral lines due to induced correlation effect, discovered first by Wolf for the single scattering case which mimics the Doppler mechanism has been extended and developed further by the present authors to study the behavior of spectral lines in the case of multiple scattering and observed shifting, as well as broadening of the spectrum. We have explored Dynamic Multiple Scatte...

A theory for the nonlinear (with respect to the electric field) Faraday effect has been developed and applied to a simple model. Within the framework of this model, our analysis shows that the ratio of the nonlinear Uerdet constant to the linear Uerdet constant is proportional to the intensity of the incident light and depends on the frequency of light, the excitation energy of the model molecu...

An observational study was performed to determine relative spectral reflectivity differences (0.41.1 microns) in the Copernicus region of the moon, as well as several other bright crater areas. A photoelectric filter photometer was used. Results suggest that: (1) spectral features do exist. (2) The spectral feature amplitude in the normalized relative spectral reflectivity curves for areas stud...