Moreover, they serve to measure the expansion velocity of the gas and the outgassing pattern of the nucleus. Observations continue The monitoring of Comet Hale-Bopp at the SEST telescope will continue, at least until March 1999. The image mostly depicts cometary dust that reflects the sunlight. 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.
North is up, East is left.
Observations are also made from time to time with other telescopes at La Silla. It shows that a very complex coma structure is still present. Due to the large size of the nucleus, probably 40 - 60 km in diameter, it will be possible to observe this comet with large optical telescopes for many years to come. Some of the most comprehensive websites may be accessed via the ESO Hale-Bopp site . 30 of the Bulletin of the American Astronomical Society .