We analyze images of BL Lacertae objects obtained with the Hubble Space Telescope WFPC2 and the F814W filter. The nine objects cover a redshift range of 0.19 to 0.997. The relatively deep images are sufficient to detect galaxies at least one magnitude below MI* (-21.4) and in most cases to three magnitudes below M*. Galaxy enhancement over the

Our HST WFPC2 survey of 110 BL Lac objects, from six complete X-ray-, radio-, and optically-selected catalogs, probes the host galaxies of low-luminosity radio sources in the redshift range /0

Line intensities, visual extinction, abundances and ionization hardness parameter for HII regions in two spiral galaxies are presented. The following galaxies have been observed: NGC 5457 and NGC 4395. In NGC 5457 have been obtained data for 338 regions. In NGC 4395 have been obtained data for 158 regions. For each region position, visual

For decades, the grand-design SAB spiral galaxy NGC 5248 has been postulated to host a short bar of semimajor axis 22" (1.6 kpc). From dynamical and morphological arguments, however, we argue that its spiral structure is being driven by a large-scale bar whose corotation radius lies at ~115" (8.6 kpc). Our estimate is based partially on a deep R

Between Oct 1999 and Jun 2001 Chandra observed M31 on a nearly monthly schedule. These observations allowed the discovery of 14 X-ray transients, a few of which were followed up with HST in an attempt to find contemporaneous optical counterparts. The transient most luminous in X-rays shows a possible U ~23 counterpart in HST imaging. The ratio of

We present the first light curves in the infrared J and K filters of VV UMa and analyze them, together with a new set of BVR light curves obtained in different runs from 1997 to 2000. Based on the spectra of VV UMa and standard stars in the region 8440-8870 Å, we classify the primary component of the binary as a type A1.5-2 V star. Evidence of