A brief description of the HEXAFLEX system is presented, which has been contrived to carry out two-dimensional spectroscopy (spectral imaging) in combination with the FLEX spectrograph at the 4.2 m William Herschel Telescope. Some astronomical illustrative examples are shown.

Photon-counting techniques have been applied to a study of the movement of the image of an unresolved star at the 50 cm telescope of the Royal Academy of Sciences, at the Roque de los Muchachos Observatory. The temporal autocorrelation function of such movement has been computed, the results are discussed in terms of atmospheric turbulence and in

Three new young objects have been found when carrying out a survey of IRAS sources with infrared colors like planetary nebulae, via low resolution spectroscopy. IRAS 14592 - 6311 and IRAS 07173 - 1733 are bright cometary nebulae, showing metal line emission very similar to V1331 Cyg, which is the prototype of a certain number of T-Tauri stars. They

The future establishment of large telescopes at the Observatorio del Roque de los Muchachos (ORM) has raised the necessity of designing a site-testing campaign, aimed specifically at selecting their emplacements, as well as characterizing correctly the local seeing behavior and the fluctuations of the turbulent field in the area covered by the

The paper presents the first results from long-slit spectra of the Seyfert galaxy NGC 4151 which give average diagnostic ratios of weak lines in the Extended Narrow Line Region (ENLR) of the galaxy and the first direct density measurement in an ENLR. These data confirm that the ENLR is kinematically undisturbed gas in the disk of the galaxy which

New narrow band images of NGC 4151, taken in excellent seeing conditions with the 4.2-m William Herschel Telescope on La Palma are presented. These reveal a wealth of detail that can be used to test models for the anisotropy of the narrow-line region.