Comet 73P/Schwassmann-Wachmann 3 (SW3) Bulletin #7

May 1, 2006

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

 

On April 29, 2006 SW3-B was observed with the Michelle mid-infrared spectrograph & imager on the 8-m Frederick C. Gillett Gemini North Telescope on Mauna Kea by D.H. Harker (UCSD) et al. These very preliminary images were obtained, in addition to spectra, through the 8-13 μm and 17-25 μm “windows” in the Earth’s atmosphere, on a night of very low precipitable water vapor. The observations were made through Director’s Discretionary time proposal GN-2006A-DD-1-23.

 

The spectra, obtained with the slit oriented along the direction of the tail, are undergoing analysis. If they are of sufficient quality, it may be possible to directly compare the mineral content and particle sizes of the dust shed in the recent “detachment” event with those leaving the cometary nucleus in a more “leisurely” fashion. Observations of C are also scheduled.

 

It will be important to compare these spectroscopic to observations obtained with other facilities on different dates. B was also observed with the InfraRed Spectrograph (IRS) of the Spitzer Space Telescope on April 17 & 19, but the data are still undergoing “pipeline processing” at the Spitzer Science Center. C was observed on March 17 (see Bulletin #4). G was also attempted using the IRS on April 17, but the observations probably failed (the data are currently at the same processing stage as those of B).

 

 

 

A second epoch of images are also to be obtained using the Multiband Imaging Photometer for Spitzer (MIPS), as part of a program headed by W. Reach (JPL). Preliminary results should be anounced in a few weeks.

 

B & G, photographed by M. Jäger & G. Rhemann on April 22.35 UT.

 

 

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