The conceptual design of the GTC optical system was completed in summer of 1997. It will be a Richey Cretien type telescope with a flat tertiary mirror to feed Nasmyth and folded Cassegrain focal stations. The telescope will have a segmented primary mirror and an entrance pupil area equivalent to a circular aperture of 10 m diameter. The details of

A detailed NLTE investigation of Fe I lines is carried out for the MACKKL quiet solar atmospheric model using a very realistic iron atomic model. This improved atomic model consists of about 250 multiplets and nearly 500 UV, optical and IR bound-bound and bound-free transitions including the regime near the Fe I continuum. The authors find and

We have performed a deep, wide-field imaging survey of the Pleiades cluster (Melotte 22) in the R and I-bands to search for very low-mass stars and brown dwarfs. The survey extends over ~ 2.5 square degrees around the cluster's center down to a ~ 90% completeness limit of R ~ 23 and I ~ 22. We find 26 objects whose location in the (I, R-I) color

We present the results of a three-year campaign of broad-band photometry in the near-infrared J, H, K and L' bands for a sample of approximately 250 giant stars carried out at the Observatorio del Teide (Tenerife, Spain). Transformations of the Telescopio Carlos Sanchez system into/from several currently used infrared systems are extended to the

A search for bright galaxies associated with radio sources from the Westerbork Northern Sky Survey (WENSS) minisurvey has been carried out. A galaxy counterpart was found for 402 of almost 10,000 radio sources. Of these a radio and optically complete sample, with a flux density limit at 325MHz of 30mJy and a limiting red magnitude of 16, can be

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