Accurate calibration of data is essential for the current generation of cosmic microwave background (CMB) experiments. Using data from the Very Small Array (VSA), we describe procedures which will lead to an accuracy of 1 per cent or better for experiments such as the VSA and CBI. Particular attention is paid to the stability of the receiver

The Canarias InfraRed Camera Experiment (CIRCE) for the Gran Telescopio Canarias (GTC) is one of the few infrared instruments in the world using a four-beam polarimeter. The classical double-beam configuration consists of a half-wave plate (HWP) and a Wollaston Prism (WP) that allow measurement of two linear polarization components of the light in

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