We present an investigation of the structure of the emission line region in a sample of 12 single-peaked Active Galactic Nuclei (AGNs). Using the high resolution Hβ and Hα line profiles observed with the Isaac Newton Telescope (La Palma) we study the substructure in the lines (such as shoulders or bumps) which can indicate a disk or disk-like

This paper presents high-resolution (0.6") spectropolarimetric observations of very quiet solar regions. We make determinations of the magnetic flux density, intrinsic field strength, and magnetic filling factor in these regions. Our results confirm other previous works in that most of the internetwork flux is in the form of intrinsically strong

We present new observations of the center-to-limb variation of spectral lines in the quiet Sun. Our long-slit spectra are corrected for scattered light, which amounts to 4-8% of the continuum intensity, by comparison with a Fourier transform spectrum of the disk center. Different spectral lines exhibit different behaviors, depending on their

ELMER is a multi-purpose instrument for the GTC designed for both, Imaging and Spectrosopy in the visible range. The CCD camera employs a E2V Technologies CCD44-82 detector mounted in a high performance LN2 Bath Cryostat based on an ESO design and a SDSU-II CCD controller with parallel interface. The design including the low-noise fan-out

We study the effect of Faraday rotation due to a uniform magnetic field on the polarization of the cosmic microwave background. Scalar fluctuations give rise only to parity-even E-type polarization of the cosmic microwave background. However in the presence of a magnetic field, a nonvanishing parity-odd B-type polarization component is produced

The final years of the XXth Century and the initial years of the XXIst Century are witnessing a revolution in the construction of large telescopes. This has been possible thanks to the availability of both thin mirror technologies and large computing power. Astronomy is thus benefiting from this. Indeed the turn of century has been rich with new