IAUC 6634 available at Central Bureau for Astronomical Telegrams.

We use statistical data giving the number of stars formed as a function of the age, assigned using the observed deterministic relation between chromospheric activity and age, to show that the temporal behaviour of star formation in the solar neighbourhood must have been chaotic during time intervals of less than 1 Gyr. We also offer evidence that

New high-resolution, high-sensitivity Westerbork Synthesis Radio Telescope Hi synthesis observations of the spiral galaxy NGC 3631 are presented. In the total atomic hydrogen map, the spiral arms are well distinguished from the interarm regions, while the sensitivity allows detection of Hi in all but a few isolated regions of the areas between the

Not Available

Aluminous mare basalts are the dominant lithology at the Luna 16 landing site in Mare Fecunditatis. For trace element analysis by micro-INAA techniques, we selected 23 of the 52 Luna 16 basaltic soil fragments studied by Kurat et al. (1976) and used a microcoring technique to extract microgram-sized samples from grain mount thin sections

The preservation of the excellent image quality of the 'Roque de los Muchachos' Observatory (ORM) is one of the most important design criteria for the enclosure of the future large telescope. Additionally, the cost of a large telescope and its instrumentation is so high that it would be regrettable if its own enclosure deteriorates the telescope