University of Arizona News Services
From: Lori Stiles, UA News Services, 520-621-1877, firstname.lastname@example.org
Contact(s): Steven M Larson, email@example.com
EDITORS/REPORTERS: If you do not use e-mail and wish to contact Larson or interview him on site while he is working at the 61-inch Mount Bigelow telescope, call Lori Stiles in UA News Services, 520-621-1877
March 18, 1997
Larson and his team will make their round-the-clock observations of Hale-Bopp on the 61-inch Mount Bigelow telescope in the Santa Catalina Mountains north of Tucson. Their last scheduled observing day, Sunday, March 23, is when the comet will make its closest approach to the Earth, at a distance of 120 million miles.
For the past several weeks, Larson, who directs the comet-imaging Bigelow Sky Survey with undergraduate and graduate students, has been using the UA's 90-inch Bart Bok Telescope on Kitt Peak and a 16-inch telescope on Tumamoc Hill to study Hale-Bopp's coma jet structure to understand the complex rotation of the comet's nucleus. (The "coma" is the visible, fuzzy head of the comet, the cloudlike mass of dust and gas surrounding the comet nucleus. The jets are the longer tails of dust and gas that professional observers use to determine the rotation rate of the comet nucleus.)
Hale-Bopp's coma structure is so complex that Larson said he enlisted a collaboration of observers in Germany, Spain, the Canary Islands, the U.S. Naval Observatory, Hawaii, Japan and elsewhere in Tucson "to combine data and make sense of what we are seeing." The observers have determined that Hale-Bopp's rotation period is about 11.4 hours, Larson said, "so we will be able to follow more than a complete rotation, which will help understand the very complex structure we see now." Larson's team is also trying to relate the location of gas molecules to where dust is streaming off Hale-Bopp, he added.
Last Sunday, March 16, Larson obtained some spectacular images with the 90-inch Bok telescope, which are to be posted soon on the Internet, he said yesterday.
The Bigelow Sky Survey Web page posts its images of comets, and other information on comets at
http://www.lpl.arizona.edu/bss/comets.html Comet Hale-Bopp Home Page