We have put into practice the technique to minimize the instrumental polarization (IP) of coude telescopes proposed by Martinez Pillet & Sanchez Almeida (1991): a λ/2-plate inserted into the optical path, with the proper orientation, cancels the IP. The compensation of the Gregory-Coude Telescope at the Observatorio del Teide turns out to fulfil

We have performed two-dimensional spectroscopy of the Seyfert galaxies NGC 5728 and 4151 in the 4500-7500A spectral range. The data (especially the [OIII] lambdalambda4959, 5007 lines), obtained using a new optical fibre system, complement previous observational work carried out by means of this technique. The two gaseous components found in NGC

We solve the line transfer problem in evolving H ii regions in order to calculate line profiles of hydrogen recombination (Hα) and forbidden oxygen ([O III] 5007) lines along several lines of sight during the photo- disruption of molecular cloud cores, or high-density condensation. The density, velocity, and ionization structure of spherically

The Taiwan Oscillation Network (TON) is a ground-based network to measure solar intensity oscillations to study the internal structure of the Sun. K-line full-disk images of 1000 pixels diameter are taken at a rate of one image per minute. Such data would provide information onp-modes withl as high as 1000. The TON will consist of six identical

A study is presented on the spectroscopic properties of a sample of star- forming dwarf galaxies in extreme density environments, as part of an ongoing project intended to evaluate the influence of the environment on the evolution of dwarf galaxies. Subsets of dwarf galaxies in nearby voids, and in the field of the local supercluster have been

A new method of representing star count data is shown which has the advantage over traditional methods of giving clear insights into the luminosity functions and density distributions of certain stellar components of the Galaxy. When this method is applied to data from the Two-Micron Galactic Survey (TMGS) it is seen that the luminosity function of