We present the first results of a combined HST/IUE/ground-based spectroscopic monitoring campaign on the Seyfert 1 galaxy NGC 5548 that was undertaken in order to address questions that require both higher temporal resolution and higher signal-to-noise ratios than were obtained in our previous multiwavelength monitoring of this galaxy in 1988 -- 89

IAUC 6106 available at Central Bureau for Astronomical Telegrams. IAUC 6106 available at Central Bureau for Astronomical Telegrams.

This paper explores the onset of thin-shell formation in interstellar shocks associated with supernova explosions. We outline a simple but useful scheme that indicates the time at which thin shell formation begins for supernova remnants (SNRs) evolving in a range of interstellar environments, extending the previous analytical models to arbitrary

The solar p-mode spectrum of very low l has already been measured with high accuracy for a sufficiently long period of time to permit the search for solar cycle variations. The longest one-site velocity observations for low l solar p-modes (Tenerife) has been used to measure the l = 1 mode splitting at the two extremes of the solar activity cycle

Not Available

We present high quality long-slit spectra of the extended narrow line region (ENLR) near the nucleus of NGC 4151. We have used these data to map the spatial variations of the emission line intensities along three slit positions: one passing radially through the nucleus along the main NE-SW axis of the ENLR and two across this axis at offsets center