Reviewing the fundamental instrumental techniques and current observational results, this book unveils the mysteries of the physical processes in the central parsec of our Milky Way: the super-massive black hole embedded in a central stellar cluster as well as the gas and dust in the circumnuclear region. The observations described cover the entire electromagnetic spectrum from decimeter radio-waves to high energy X-ray and k-rays, and a comprehensive summary of up-to-date astrophysical interpretations is given. The emphasis is put on observational techniques, image processing aspects, and a detailed presentation of the most cutting-edge work carried out in the near-infrared wavelength regime. These recent results include both the first orbits of stars around the central black hole and the multiwavelength variability of the central source.

# Observational Techniques: # The GC Across the Electromagnetic Spectrum # NIR Imaging Through the Atmosphere # Speckle Imaging # Single Telescope Adaptive Optics # Cleaning and Deconvolution # Future IR Interferometry # Observational Results: # The Discovery of Sagittarius A* # Large-Scale Structures at the Galactic Center # The Circum Nuclear Disk # The Mini- Spiral # Radio Filaments # Near-Infrared Images of the Central Stellar Cluster # The Radio and Infrared Positional Reference Frames # Number Density Counts # Polarization of Filaments and Stars # Stellar Velocities and Orbital Accelerations # Spectroscopy # Star Formation at the Galactic Center? # Sgr A* Across the Electromagnetic Spectrum # Astrophysical Results: # The Stellar Velocity Field # Scenarios for Star Formation at the Galactic Center # The Central Dark Mass # Stability of the Enclosed Dark Mass # Agglomerations of Exotic Particles? # The Central Stellar Cusp # Analysis of Stellar Orbits Near the Central Black Hole # The Central Black Hole # Comparison to Nuclei of Other Galaxies # Massive Black Holes at High Redshifts