The orbital motion of Linus around (22) Kalliope

The best-ever images of the moon Linus orbiting Asteroid (22) Kalliope. It was obtained with the SINFONI Adaptive Optics Module and a high-angular-resolution near-infrared Test Camera during commissioning in June 2004. At minimum separation, the satellite approaches Kalliope to 0.33 arcsec, i.e. the angle under which a 1 Euro coin is seen at a distance of 15 kilometers. At maximum separation, the angular distance is nearly twice as large. For clarity, the brightness of the asteroid has been artificially decreased by a factor of 15, to the level of the moon. This image processing technique also permits to perceive the variation of the asteroid's shape as Kalliope spins around its own axis with a period of 4.15 hours. The asteroid, with an angular diameter of 0.11 arcsec, is barely resolved in these VLT images (resolution 0.06 arcsec at wavelength 2.2 µm). The satellite measures about 50 km acroos and orbits Kalliope at a distance of about 1000 kilometers.