July 21 (UT). The NASA/Infrared Telescope Facility
reports observing a bright plume associated with the impact
of fragment R, at 5:40 UT, using the MIRAC2 mid-infrared array
camera. The fireball was observed at wavelengths of 7.85, 10.2,
and 12.2 um at intervals of 50 seconds per cycle.
The emission increased at all three wavelengths for 5-10
minutes, then decayed on a slower time scale. At its brightest,
the fireball's surface brightness was at least 50 times that
of Jupiter at all three wavelengths.
The NASA/IRTF Comet Collision Science Team