Observations of carbon monoxide in comet Hale-Bopp.

The recently discovered comet Hale-Bopp (C/1995 01) sports a bright dust coma even though it is still far from the sun (presently 6 astronomical units). This feature has attracted considerable interest in the public and scientific arenas. The comet is headed toward perihelion at 0.92 astronomical unit in April 1997 and is widely expected to then become a spectacular naked-eye comet. With millimeter-wave observations, carbon monoxide (CO) has been identified as the driver for the early activity observed in Hale-Bopp.