It is shown how present uncertainties in the ability to compute collisional cross sections for rotational transitions can lead to order of magnitude errors in the interpretation of the observed antenna temperatures for rotational emission lines from interstellar clouds. The framework within which improved cross sections can be derived is described

Data from solar line of sight velocity measurements are presented to demonstrate the existence of a synodic signal with a 6.5 m/sec amplitude. Recordings of alternate measurements of the resonantly scattered light intensity were made at 1 sec intervals and a mean ratio for the laboratory and solar lines was calculated over a 42 sec interval

An automatic and fast procedure was implemented to determine Te and log g from the comparison of the UV S 2/68 spectra with the Kurucz models. The method has been applied to all A and F stars with (B-V)0 greater than or equal to 0 and luminosity classes III, IV, IV-V, and V, included in the Ultraviolet Bright-Star Spectrophotometric Catalogue. From

Calculations of atmospheric transmission through the M (5 microns) atmospheric window, at a resolution of 10 to the 3rd power are presented for sites at the Observatorio del Teide, Tenerife and the NHO, La Plama in the Canary Islands. We use a standard midlatitude atmospheric model and absorption line strengths for the known molecular species

The 2(1,1) - 2(1,2) rotational transition of HDO has been detected towards the KL position at the center of the OMC-1 at a velocity of +5.5(+ or - 1.3)km/s, corresponding to emission from the central core. This measurement is combined with previous estimates of the H2O abundance close to KL to obtain a ratio of the concentration of HDO to that of

Position data of sunspot groups from the period 1874-1902 are used to investigate the differential rotation of the Sun and the meridional motions of the sunspots. The equatorial velocity is higher than in the period 1940-1968 investigated by Balthasar and Wöhl (1980), while differences between the northern and southern hemispheres are less. For