The graph below shows a ten minute period on the afternoon of Thursday, June 7, 2001. The data is from the field mill positioned at the base camp. Our time axis has not yet been compared to GPS and is approximate. Key events were noted with a voice recorder giving approximately one-minute resolution. Within these limits, the two prominent events are believed to be identifiable as follows:

1. The broad event centered at 4 minutes corresponds to six small dust devils that were rotating together around a common center. The time corresponds to 2:57 p.m. local Tucson time. The formation passed by the instrument moving south then turned easterly, effectively bending around the site.This explains the unusual width of the signal. The closest approach was about 10-15 meters.
2. The large peak centered at about 5.5 minutes corresponds roughly to 2:58.5 local time. It represents a fair sized dust devil approximately 6 to 8 m in diameter which scored a direct hit on the camp and moved on without changing direction. The field mill was pegged at its maximum scale for about 9 seconds.

NOTE: One would hope that data analysis with all instruments contributing would allow us to replay a large event with accurate, sub-second resolution of position, velocity, size, and wind speed. We should be able to completely characterize it point by point as it moves. If for any reason we cannot do this we should understand how to make it happen before we go out again.