We explain the linear polarization of the Ca ii infrared triplet observed close to the edge of the solar disk. In particular, we demonstrate that the physical origin of the enigmatic polarizations of the 866.2 and 854.2nm lines lies in the existence of atomic polarization in their metastable 2D3/2 , 5/2 lower levels, which produces differential

In this summary, a brief review is given of the main results presented during the workshop on astronomical site evaluation of San Pedro Mártir in Northern Baja California, Mexico, leading to to a summary of the most significant results related to San Pedro Mártir as a site for housing optical and infrared telescopes.

Echelle spectrophotometry of the planetary nebula NGC 5307 is presented. The data consist of Very Large Telescope Ultraviolet Visual Echelle Spectrograph observations in the 3100-10360 Å range. Electron temperatures and densities have been determined using different line intensity ratios. We determine the H, He, C, and O abundances based on

Line-of-sight velocity fields in an irregular sunspot (NOAA 8990) have been determined from Stokes-I spectra of the line Fe I 630.15 nm, obtained with the La Palma Stokes Polarimeter at the Swedish Vacuum Solar Telescope on May 13, 2000. We show and discuss the resulting velocity maps, the dependence of velocities on the continuum intensities, and

Statistics are presented covering 20 years of use of the 2.1m telescope of the Observatorio Astronómico Nacional at San Pedro Mártir, Baja California, Mexico. As in the previous compilation, the fractional number of nights with totally clear, partially clear and mostly cloudy skies were determined. The fraction of nights lost due to bad weather was

A 50 min time series of one-dimensional slit-spectrograms, taken in quiet sun at disk centre, observed at the German Vacuum Tower Telescope (Observatorio del Teide), was used to study the global and spatial variations of different line parameters. In order to determine the vertical structure of the photosphere two lines with well separated