Observations of comet Hale-Bopp from La Silla

The image shows Comet Hale-Bopp, as imaged on October 19, 1998, in visible light and with the DFOSC instrument at the Danish 1.5-m telescope on La Silla. At this time, the comet was about 1,000 million kilometer (6.7 AU) from the Earth and the Sun. Although well beyond Jupiter's orbit, it is very obvious that strong nucleus activity is still present — the large coma extends well beyond the field of view (200 x 200 arcsec or about 1 million km at the distance of the comet). The image mostly depicts cometary dust that reflects the sunlight. The coma is very asymmetric with more material in the northern hemisphere (above). There are also some jets embedded in the coma which indicate that some of the dust is emitted from active regions on the surface of the nucleus. The background stars are slightly elongated since the telescope followed the motion of the comet in the sky during the exposure. Technical information : 5-min exposure through a broadband V-filtre. North is up, East is left. Observers: Kirsten Kraiberg Knudsen (Copenhagen University, Denmark) and Hermann Boehnhardt (ESO/Chile).