High resolution, high S:N spectra are used to determine the abundances of Fe, Ni, Ca, Al and Si in 25 field dwarfs with -1.2 < [Fe/H] < +0.3. The authors find overabundances for Al, Ca and Si in stars with -1.2 < [Fe/H] < -0.5 and solar [Ni/Fe] over the whole studied range.

The authors have applied to the Sun a method for calibrating, in absolute flux units, Ca II H profiles of late-type stars. After comparing, in the region 3948 - 3882 Å, an LTE synthetic spectrum with the data of the solar flux atlas by Kurucz et al. (1984), they have defined the wavelength ranges where observations agree with computations, based on

The correspondent mass accretion rate values for SS Cygni are deduced from the He II 1640 A emission line equivalent width values in all good available IUE low resolution spectra, using the optically thick boundary-layer model developed by Patterson and Raymond (1985). In the rising and declining phase of an outburst, the mass accretion rate value

A sample of active galaxies and quasars was observed with a photon-counting detector (IPCS) working in time-resolved imaging mode. The observing and data-reduction technique involves taking short-exposure images, selecting from those the sharpest, and adding them up after having corrected them for image motion. Final resolutions of a few tenths of

CCD photometry of the jet in the Thuan-Gunn r and g filters obtained under good seeing conditions is presented. Elliptical models of the underlying stellar emission were subtracted from the reduced and calibrated images. The high signal to noise ratio and good spatial resolution make it possible to determine very accurately the morphological

IAUC 4516 available at Central Bureau for Astronomical Telegrams. IAUC 4516 available at Central Bureau for Astronomical Telegrams.