The experimental study of sodium layer is relevant to fields such as adaptive optics, in particular for laser guide star generation. We have developed an instrument to make systematic measures of the most relevant parameters of the sodium layer above canarian observatories. The measurement provides information about sodium layer: the medium

IUE spectra of Mg II h and k in late type dwarfs and giants were used to detect and measure absorption components due to the LISM. This technique gives a method of probing the awkward range from d = 3 pc to d = 80 pc from the Sun. In spite of interpretational uncertainties the HI component of the LISM can be plotted well enough to confirm it as a

Simple gravitational lens models usually suffice to reproduce the positions of lensed quasar images, but they have problems to reproduce their optical flux ratios. The so-called flux ratio anomalies are thought to be produced by small-scale structure in the lens galaxies (microlensing).

We present a cross-correlation of the European Large Area Infrared Space Observatory (ISO) survey (ELAIS) with the ELAIS Deep X-ray Survey of the N1 and N2 fields. There are seven Chandra point sources with matches in the ELAIS Final Analysis 15-μm catalogue, out of a total of 28 extragalactic ISO sources present in the Chandra fields. Five of

We present synthetic spectral energy distributions (SEDs) for single-age, single-metallicity stellar populations (SSPs) covering the full optical spectral range at moderately high resolution [full width at half-maximum (FWHM)=2.3Å]. These SEDs constitute our base models, as they combine scaled-solar isochrones with an empirical stellar spectral

TNOs (50000) Quaoar and 2002 TX300 were observed in the framework of a long-term program to study the surface properties of TNOs, Centaurs and comet nuclei using the Italian 3.58 m Telescopio Nazionale Galileo (TNG) at "El Roque de los Muchachos" Observatory (La Palma, Spain). Near-infrared spectra of both TNOs and visible spectrum of 2002 TX300