The 1997 Mutual Event Occultations of Io

R. R. Howell (U. of Wyoming), J. R. Spencer, J. A. Stansberry (Lowell Observatory)

The 1997 series of mutual events includes a large number of occultations of Io by other Galilean satellites, which are being observed in the 3-5 micron region at Lowell Observatory and the Wyoming Infrared Observatory. Photometry of hotspot occultations currently provides the highest infrared spatial resolution possible either from the ground or from spacecraft. Furthermore, this series of events fortunately is occurring during a brightening of Loki and during the Galileo mission. The high resolution data can provide important constraints on the nature of the volcanic activity. Although the observing weather for the events during March and April has been disappointing some data were obtained during the event on March 28, and additional observations are scheduled for events on June 13, 21, and 28. Further observations are planned for events during the late summer and fall. In addition to presenting the expected 1997 data, this paper will discuss analysis techniques for mutual event data using the 1991 series of observations, which also occurred during a Loki brightening.