A case of cancellation of magnetic fields is observed during the decay of a small active region. Three different sources of information were simultaneously used: high resolution magnetograms, chromospheric Ca II filtergrams and transverse velocity fields. A magnetic structure is apparently dragged to the network by the supergranular velocity field

Radial velocity measurements of a group of Ap stars were obtained in May and December 1987 using a Fabry-Perot interferometric stellar oscillation spectrometer that has been improved to enable the instrument to be referenced to the Cd blue line. Observations of the rapidly oscillating Ap stars 33 Lib and HR 1217 were analyzed in order to search for

The evolution of the emission line ratios of a photoionized cloud described by standard BLR parameters which is exposed to a varying ionizing continuum is studied. The hardness of the ionizing distribution was varied by decoupling the UV increase from that of the X-ray component. After many tests using various ionizing distributions, it became

IAUC 4830 available at Central Bureau for Astronomical Telegrams.

Optical spectroscopy, H-alpha interferometry, and near-IR mapping and photometry of the bipolar H II region S201 are reported. The observations are used to place constraints upon the energetics of the H II region as well as to provide a clearer understanding of the IR structure. The exciting star is coincident with a central bar of obscuring

A spectral ratio, similar to that of von der Lühe (1984), is proposed to derive information on the degradation of the mean granular power spectrum at a position outside the disk centre. It has the advantage that the modulation transfer function is obtained directly from the data, without making any assumption on turbulence theory to describe the