Comet Hale-Bopp: alive and spewing.

The comet of the century is finally out of view of telescopes in Hawaii, and David C. Jewitt couldn't be happier.

After faithfully monitoring Hale-Bopp since August 1995, including every weekend for the past 9 months, the University of Hawaii astronomer and his colleagues have gathered a plethora of information on the icy body's submillimeter emissions. The relentless observation schedule, however, drove the team "absolutely nutty," Jewitt says.

The observations, taken with the James Clerk Maxwell Telescope near the summit of Kea, reveal the relative proportion of carbon, nitrogen, oxygen, and sulfur isotopes in material ejected by the comet. The group deduces from these data that Hale-Bopp probably coalesced in the frigid outer reaches of the infant solar system.

Researchers believe that comets generally come from either of two reservoirs -- the Kuiper belt or the more distant Oort Cloud -- but a tiny number may be interlopers from another planetary system. For Hale-Bopp, at least, "we found the boring result," says Jewitt. He and his colleagues describe their findings in the Oct. 3 Science.

Jewitt told Science News that the team's long-term monitoring of Hale-Bopp indicates that on its retreat from the sun, the comet is spewing hdyrogen cyanide and carbon monoxide as copiously as it did on its approach.

Hale-Bopp is now more than three times farther from the sun than it was at its closest approach, on April 1, and is visible only from the Southern Hemisphere. Observations from the European Southern Observatory in La Serena, Chile, show that the comet, though considerably dimmer than it was last spring, remains active. Jets of dust endow the comet's coma, or shroud of gas and dust, with the same porcupine appearance it had in the latter half of 1996.