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The status of kinematic observations in Local Group dwarf spheroidalgalaxies (dSphs) is reviewed. Various approaches to the dynamicalmodelling of these data are discussed and some general features ofdSph dark matter haloes based on simple mass models are presented.
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).
We present results from orbit integrations for the globular clusters M 3 and M 92. Absolute proper motions recently measured from Tautenburg Schmidt plates and a three-component mass model for the Galaxy have been used to derive the galactic orbits of these clusters. Orbital parameters and the influence of observational uncertainties on the determination of the orbits are discussed.
Palomar and Tautenburg Schmidt plates with a base line of about 35 years have been measured with the Automated Photographic Measuring (APM) system in Cambridge (UK) in order to obtain the proper motions of the Galactic dwarf spheroidal satellites (dSph) in Draco and Ursa Minor with respect to a well defined extragalactic reference frame. The investigations were encouraged by the accuracy level achieved for the mean absolute proper motions of galactic globular clusters (0.05 arcsec/century from 25 years base line Tautenburg plate pairs) which is comparable to the expected proper motion of the Draco and Ursa Minor dSph assuming tangential motions of about 100 km/s. Different methods for the removal of systematic errors in the absolute proper motion introduced by the measuring and reduction process are discussed. The more accurate relative proper motions of individual stars in both dSphs obtained by Stetson (1980) and by Cudworth, Olszewski & Schommer (1986) provide an external comparison and are also used to obtain the mean absolute proper motion of the dSphs.
We describe how the application of techniques which utilise all the information contained in multi-colour surveys of stellar-like objects can be employed to detect quasars over an extended redshift range. The method is particularly effective for the identification of quasars with redshifts z>2.2 where the application of the ultra-violet excess criterion breaks down. Spectroscopy of a small sample of objects from the first survey field has resulted in the detection of two new faint quasars with redshifts z=3.42 and z=4.01 (ref. 1).
By applying the principle that all stellar image profiles should be identical apart from a scale change, we can derive a relative calibration for a photographic plate without use of calibration spots or other indirect means.
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