Learning About Young Globular Clusters

IV-N yes RG 715 I 90 min -19 (up to 5 hours) of selected objects through the available Ha and S I1 interference filters which have a useful field of about 2°. The approximate limiting magnitudes for direct plates are quoted in the table. They depend on the seeing; the numbers given are for medium seeing and deeper plates are obtained under excellent conditions. These values may possibly be further improved after the installation of the new Grid Processing machine in November 1988. At the same time, tests are being made of the new Kodak T-max emulsion, although the sensitization appears to be more difficult than first expected. We shall report in one of the next Messenger issues about the initial results. The ESO Schmidt telescope is equipped with one of the world's largest objective prisms, giving a dispersion of about 450 Nmm at Hy. Under good seeing conditions, it is possible to obtain widened spectra which allow MK classification, down to magnitude 14.5-15.0. Unwidened spectra give limiting magnitudes, approximately 2-3 magnitudes fainter. The performance is critically dependent on the seeing, as is the case for all objective prism work. The UBK 7 glass is ultraviolet transparent. In the future, the 30 x 30 cm plates will be scanned on the refurbished two-coordinate measuring machine at the ESO Headquarters (formerly the S-3000 machine). With a new CCO head and much improved software and large computer storage space, it will become possible to perform "blinking" of large areas. This will greatly speed up the extraction of data from the photographic plates and may give a new impetus to the use of the ESO Schmidt as a powerful survey instrument. H.-E. SCHUSTER and R. M. WEST Monitoring SN 1987A