Coordinated programs for comet Halley

Because comets are so difficult to observe, it is essential to coordinate observations from a variety of telescopes in order to fully understand their behavior. The apparition of Comet Halley represents a unique opportunity for coordinated programs because this is the only predictable comet which is routinely bright enough for the many observational programs desired. The International Halley Watch is playing an advocacy and coordinating role in the observations of Halley. Coordinated photographic observations will provide a record of the development of jets in the coma and of the motion of features in the tail. Coordinated photometry will provide both the heliocentric variation in vaporization and also the details of the outbursts thought to occur in most comets. Coordination with larger optical telescopes and with radio and infrared telescopes will allow a more complete understanding of the physical and chemical processes occurring in comets. Examples, of course, must still be drawn from observations of previous comets but they illustrate the results expected from Halley.