[meteorite-list] A Comet Turns On (Comet P/2004 TU12)

[Ron Baalke]

http://skyandtelescope.com/news/article_1392_1.asp

A Comet Turns On
Sky & Telescope
November 15, 2004

What began as the routine discovery of a near-Earth asteroid 
on October 10th took on a curious and dramatic twist a month 
later when the new find suddenly developed a short tail. 
Franco Mallia, Gianluca Masi, and Roger Wilcox first spotted 
the pencil-thin appendage in CCD images they'd taken on 
November 11th with a 0.36-meter reflector at Las Campanas 
Observatory, Chile. The tail independently turned up in CCD 
frames taken less than a day later by Juan Lacruz in La Canada, 
Spain. No one yet knows what caused the tail to form (two other 
asteroids-turned-comets, 107P/Wilson-Harrington and 
133P/Elst-Pizarro, have been discovered in recent decades). 
But observers are certain it wasn't there when Rob McNaught 
first recorded the asteroid, designated 2004 TU12, using a 
0.5-meter Schmidt telescope at Australia's Siding Spring 
Observatory. A preliminary orbit issued by the Minor Planet 
Center puts Comet Siding Spring (now officially P/2004 TU12) 
between the orbits of Earth and Mars, near the perihelion of a 
looping, 5.3-year-long track. At 14th magnitude, it's too 
faint to be seen visually in small telescopes.

For more details about Comet Siding Spring, including a 
time-lapse image sequence, see Masi's Web site: 

http://www.bellatrixobservatory.org/neo.html.