From measurements of Tautenburg Schmidt plates with the APM facility in Cambridge we obtained absolute proper motions of the Galactic globular clusters M 3 and M 92 directly with respect to large numbers of background galaxies (Scholz et al. 1993, 1994). We have extended our work to the dSphs in Draco and Ursa Minor (Scholz & Irwin 1994) and to other Galactic globular clusters using Tautenburg, Palomar and UK Schmidt plates. Combining our absolute proper motion of a cluster with its known radial velocity and distance (using common parameters of the solar motion) we derive the cluster orbit in the Galaxy (cf. Odenkirchen & Brosche 1992).

Low-pressure plasma deposition (LPPD) was used to synthesize an in-situ MoSi2/SiC composite using 100% methane (CH4) as a powder carrier gas. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) identified MoSi2, Mo5Si3, Mo5Si3C, Si02, and SiC as the phases present in the composite. XRD and XPS revealed ∼6 vol% SiC in the as-sprayed material. Annealing of the as-sprayed composite increased the SiC content to ∼8 vol% while reducing the Si02 volume fraction. Transmission electron microscopy studies revealed a fine homogeneous distribution of SiC and/or carbide particles at prior splat boundaries in the MoSi2 matrix. Wavelength dispersive spectroscopy (WDS) confirmed the increased presence of carbon in the in-situ materials. Fracture toughness measurements yielded values on the order of 10 MPa m½ for annealed composites. The creep behavior of the LPPD reactive spray composite dramatically improved compared to unreinforced LPPD MoSi2. Additionally, the creep behavior was shown to be equal to or better than that of powder metallurgy MoSi2/SiC composites containing higher percentages of SiC.

A programme for the determination of proper motions and photographic B, V, R magnitudes for stars up to 18m within a 4° by 4° region centered near Alcyone is described. We use MAMA measurements of plates taken with Tautenburg and OCA Schmidt telescopes as well as with the double refractor of Bonn and Carte du Ciel plates. To check the stability of the solution three different methods of reduction are applied.

According to the results of the pilot programme a final proper motion accuracy of about 2 mas/a can be achieved for the majority of stars in the survey.

Besides the link of the HIPPARCOS reference frame to extragalactic objects via radio stars or by the HST, also photographic astrometry is able to calibrate the HIPPARCOS proper motions with regard to an inertial system. Numerical simulations have shown that even with a very small number of well-distributed link fields (3 to 5) the photographic method is competitive with other techniques.