Context: For the first time, spectroscopic galaxy redshift surveys are enabling galaxies to be studied with the nearest quasars. This allows the dependence of the activity of a quasar on its environment to be studied in a more extensive way than before. Aims: We study the spatial distribution of galaxies and properties of groups of galaxies in the

Aims: We completed observations with the Effelsberg 100-m radio telescope to measure the polarised emission from a complete sample of compact steep-spectrum sources and improve our understanding of the physical conditions inside and around regions of radio emission embedded in dense interstellar environments. Methods: We observed the sources at

In a multiwavelength programme dedicated to identifying optical counterparts of faint persistent X-ray sources in the Galactic bulge, we find an accurate X-ray position of SAX J1712.6-3739 through Chandra observations, and discover its faint optical counterpart using our data from EFOSC2 on the ESO 3.6-m telescope. We find this source to be a

El decaimiento de las regiones activas en en Sol muestran dos fases, a saber: una fase linieal de pérdida de flujo local, y otra fase plana. A partir de los datos del instrumento SoHO/MDI hemos estudiado la evolución de tres regiones activas, cuantificando por primera vez estos ritmos de decaimiento, así como las cancdelacioones y pérdidas de flujo

FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the GTC) will be a NIR (1-2.5 μm) imager and Integral Field Unit spectrograph to operate with the Adaptive Optics system of the 10.4 m GTC telescope. FRIDA will offer broad and narrow band diffraction-limited imaging and integral field spectroscopy at low, intermediate and high

Available from the Minor Planet Center.