We introduce a pixel-to-pixel comparison method to detect the temperature anisotropies on the Cosmic Microwave Background induced by the time variation of gravitational potentials along the line of sight. We demonstrate it to be more sensitive than the cross-correlation method used in previous studies. We compare the recent WMAP data with templates

En esta tesis se estudia la influencia del efecto microlente gravitatorio sobre las líneas anchas de emisión de los cuásares usando las estimaciones más recientes del tamaño de la región de líneas anchas y la relación de escalado que existe entre este tamaño y la luminosidad. El efecto microlente, causando por estrellas u otros objetos compactos

We study the rotation rates and electric dipole emission of hydrogenated icosahedral fullerenes under the physical conditions of the dark cloud (DC) LDN 1622. The abundance of fullerenes is estimated by fitting theoretical photoabsorption spectra to the characteristics of the ultraviolet (UV) bump extinction in DCs. The UV bump appears to be well

We present the results of first spectropolarimetric observations made with the Interferometric Bidimensional Spectrometer (IBIS) at the NSO/Dunn Solar Telescope. The use of narrowband imaging and post-facto reconstruction techniques allows for observations close to the diffraction limit of the vector magnetic field. We will show observations of the

We present high resolution optical spectroscopic observations of IRAS 09425-6040, a peculiar, extremely red, C-rich AGB star showing prominent O-rich dust features in its ISO infrared spectrum attributed to crystalline silicates. Our analysis shows that IRAS 09425-6040 is indeed a C-rich star slightly enriched in lithium ({log (Li/H) + 12} ˜ 0.7)

We are currently developing the calibration programme for GTC using techniques similar to the ones use for the space telescope calibration (Hammersley et al. 1998, A&AS, 128, 207; Cohen et al. 1999, AJ, 117, 1864). We are planning to produce a catalogue with calibration stars which are suitable for a 10-m telescope. These sources will be not