The BL Lac 1517+656 is an extreme example of its class. Not only is it the most optically luminous BL Lac known but this extreme emission extends to both radio and X-ray frequencies. In our WFPC2 snapshot survey we discovered a series of arcs describing a 2 arcsecond ring surrounding the object. Follow-up observations with additional WFPC2 bands

The pulsating DAV white dwarf G185-32 was observed with the Whole Earth Telescope in 1992, during XCov8. We briefly report on the weighted Fourier transform of the data obtained.

We present the analysis of UV and optical spectra of M 33 early B-type supergiants. Stellar parameters, metal abundances (Si, Mg, O and N) and mass loss rates are derived from anlyses of optical spectra by means of non-LTE unblanketed unified model atmospheres (FASTWIND code, Santolaya-Rey, Puls & Herrero 1997). These analyses use wind terminal

We present preliminary results on the XMM-Newton Survey Science Centre medium sensitivity survey, with 0.5-4.5 keV flux limit 2x 10-14 erg cm-2 s-1. At present, 19 fields have been examined with a total of 239 X-ray sources. Identifications for about 2/3 of these reveal that type 1 AGN dominate, but type 2 AGN, absorption-line galaxies and clusters

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We present a study focusing on the nature of compact groups through the study of their elliptical galaxies. We determine central velocity dispersions (σo) for 18 bright elliptical galaxies located in the core of Hickson compact groups and a control sample of 12 bright bona fide ellipticals located in the field or very loose groups. Several tests