First Stereo Results from the High Resolution Fly's Eye Air Fluorescence Detector

Abstract The second site of the High Resolution Fly's Eye air flourescence detector,known as HiRes2, located at Camel's Back Ridge in Dugway, Utah has been in operation since Spring 1999. Stereo observations of cosmic ray air showers have been made using the HiRes2 site in conjunction with the HiRes1site located at a distance of 13 km. Stereo observations enable the location of air showers to be more reliably determined using geometrical considerations. The determination of the energy of the primary cosmic ray particle and the depth of the shower maximum, which is useful for composition studies, are thereby improved. First results from the stereo observation of cosmic ray air showers using both detector sites will be described