The distribution of arrival times of the Cherenkov light at the center of a shower is highlycorrelated with the altitude of emission distribution of light in a shower. This distribution is alsoexpected to be highly correlated with the particle density with altitude distribution in the shower.

5.2 Timing Focusing Occurs Independently of Shower-max.

The concentration of the arrival time of light in a zenith shower occurs in an annulus aboutthe shower center. This annulus has an inner radius of about 80 m and extends out to 160 m (thoughmost sub 100 GeV showers will not produce detectable light out to this extreme). This focusingcreates a wavefront that is to first order conical in shape and is independent of both shower energyand the altitude of shower max. This is in direct opposition to the timing of the light at the center ofthe shower which is totally dependent on the emission altitude distribution.

5.3 Inclined Showers Have Timing Properties Similar to Zenith Showers

The Cherenkov light from inclined showers displays the same characteristics seen in zenithshowers. The center pulse shape is a good measure of the altitude of emission distribution. Focusingof the timing of the light occurs in an annulus about the center of the shower. For inclined showersthis annulus becomes elliptical in shape with its long axis being in the vertical plane of theinclination. Again as for zenith showers this elliptical annulus occurs independently of shower maxand shower energy, and has a conical envelope. The shape of the cone will vary slightly withincreasing inclination.