Aims: Our main objective is to develop a denoising strategy to increase the signal to noise ratio of individual spectral lines of stellar spectropolarimetric observations. Methods: We use a multivariate statistics technique called Principal Component Analysis. The cross-product matrix of the observations is diagonalized to obtain the eigenvectors

From the analysis of the color-magnitude diagrams and color functions of four wide LMC fields located from ~=2 to 6 kpc from the kinematic center of the LMC we present evidence that, while the oldest population is coeval in all fields, the age of the youngest component of the dominant stellar population gradually increases with galactocentric

The Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) is the first light instrument for the 10.4 meters Gran Telescopio de Canarias (GTC). It's a 8.5 × 8.5 arc-min visible camera; a set of grisms provides low resolution spectroscopic capability. In this contribution the accessories and mountings for alignment are

Aims: We study the dynamical status of the poor, low X-ray luminous galaxy clusters Abell 610, Abell 725, and Abell 796 (at z = 0.1, 0.09, and 0.16, respectively), containing diffuse radio sources (relic, relic, and possible halo, respectively). Methods: Our analysis is based on new spectroscopic data obtained at the William Herschel Telescope for

New dispersive elements providing relative high resolution (R=2200) have been recently incorporated in the near infrared spectrograph LIRIS. These elements are founded on a rather novel design based on a diffractive pattern engraved in fused silica, which is placed between two prisms. These new components are pushing forward the scientific

Context: The compact association Cygnus OB2 is known to contain a large population of massive stars, but its total mass is currently a matter of debate. While recent surveys have uncovered large numbers of OB stars in the area around Cyg OB2, detailed study of the optically brightest among them suggests that most are not part of the association