A survey of 380 sq. deg. of the sky with the 1m Schmidt telescope at the Observatorio Nacional de Llano del Halo and the QUEST camera has found 498 RR Lyrae variables lying from 4 to 60 kpc from the Sun. We describe the halo substructure revealed by these data and the results of measuring some of the stars' radial velocities and metal abundances.

We present Sloan g and i imaging from the Gemini Multi-object Spectrograph (GMOS) instrument on the Gemini North telescope for the globular cluster (GC) system around the Virgo galaxy NGC 4649 (M60). Our three pointings, taken in good seeing conditions, cover an area of about 90 square arcmin. We detect 2151 unresolved sources. Applying colour and

High-resolution spectra of a sample of all known stars more luminous than MV=+6.5 and closer than 15 parsecs are being analyzed spectroscopically in order to derive their effective temperatures and surface gravities. These spectra are taken from the database of "A Spectroscopic Survey of Stars in the Solar Neighborhood". The analysis utilizes a

Although it is clear that the circumnuclear regions of galaxies are intimately related to their host galaxies, most directly through their bars, it remains unclear what exactly initiates and fuels nuclear stellar (starburst) and non-stellar (AGN) activity. Deviations from axisymmetry in the gravitational potential of a galaxy, set up by a bar or an

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We report on our ongoing efforts to probe for extrasolar giant planets in the Sigma Orionis open cluster. With an age of about 3 Myr, a distance of about 440 pc and very low reddening, this cluster provides a privileged hunting ground for brown dwarfs and superplanets. Several L dwarfs and one T dwarf have been identified in the cluster. Assuming