Comet 73P/Schwassmann-Wachmann 3 (SW3) Bulletin #10

May 22, 2006

Michael L. Sitko, University of Cincinnati & Space Science Institute

There has been very little exciting news in the past week. No updates from the Lunar & Planetary Lab group (Hergenrother et al.). However, Dave Schleicher (Lowell Observatory) has reported new measurements of OH, CN, C₂, and dust from May 17 & 18, indicating that B has become less active. He predicted that C would once again be brighter than B, unless B undergoes another outburst.

Infrared measurements obtained on May 18 & 19 UT by Sitko, Russell, Polomski, Ford & Crawford using NASAs Infrared Telescope Facility (IRTF) and The Aerospace Corporation’s Broadband-Array Spectrograph System (BASS) showed that C was indeed brighter than B, but the brightness of C was quite variable on the latter day. These observations were made during daylight, but the comets were very bright and easily centered in the instrument.

Seiichi Yoshida has updated the light curves for the various components, an example of which is shown below (for the complete set of light curves go to http://www.aerith.net/comet/catalog/0073P/2006.html).

As was suggested in an earlier bulletin, G had probably undergone severe disintegration, and was likely to fade from view prematurely. Recent visual observations indicate that this is in fact the case. While B and C have continued to brighten since mid-April, G has faded.

For more information, contact:

Mike Sitko

Dept. of Physics, University of Cincinnati sitko@physics.uc.edu Phone: 513.556.0642

& Space Science Institute, Boulder, CO sitko@spacescience.org