Rapidly oscillating Ap (roAp) stars exhibit an astrophysically interesting combination of strong, dipolar-like magnetic fields and high-overtone p-mode pulsations similar to the Sun. Recent time-resolved spectroscopy of these stars unravelled a complex picture of propagating magnetoacoustic pulsation waves, with amplitude and phase strongly

We present a detailed study of the stars of the NASA InfraRed Telescope Facility (IRTF) spectral library to understand its full extent and reliability for use with stellar population (SP) modeling. The library consist of 210 stars, with a total of 292 spectra, covering the wavelength range of 0.94 to 2.41 μm at a resolution R ≈ 2000. For every star

We present unresolved single stellar population synthesis models in the near-infrared (NIR) range. The extension to the NIR is important for the study of early-type galaxies, since these galaxies are predominantly old and therefore emit most of their light in this wavelength range. The models are based on a library of empirical stellar spectra, the

The site selection for the future European Large Telescope (E-ELT) is a key issue within the European proposal funded by the European Union (EU), within the ``ELT design study'' proposal. The organization, working scheme and baseline frameworks are reviewed. For the definition of the working package WP12000 ``Site Characterization'', important use

The Observatorio Astronómico Nacional at San Pedro Mártir is located at 31°02'40''N and 115°28'00''W on the summit of the Sierra San Pedro Mártir on the Baja California peninsula, Mexico, at 2800 m above sea level. The results of more than three decades of site characterization work are summarized. These cover the following aspects: weather, cloud

We present eight monitoring seasons of the four brightest images of the gravitational lens SDSS J1004+4112 observed between 2003 December and 2010 October. Using measured time delays for the images A, B, and C and the model predicted time delay for image D we have removed the intrinsic quasar variability, finding microlensing events of about 0.5