Update 12/09/05: with a cut at 45 degrees on the reconstructed shower angle,
the aperture in m^2 at each zenith angle is:
A(cosZA = .60) = 3.50 x 10^3
A(cosZA = .70) = 6.30 x 10^4
A(cosZA = .80) = 3.09 x 10^5
A(cosZA = .90) = 4.78 x 10^5
Using this fit, the integrated aperture is 6.87 x 10^5 m^2 sr.
I dropped 1000 showers from two AIRES runs at each zenith angle (using AIRES showers ZA60_01, ZA60_04, ZA70_01, ZA70_05, ZA80_01, ZA80_05, ZA90_01, ZA90_06).
Aperture in m^2 at each zenith angle:
A(cosZA = .60) = 4.30 x 10^4
A(cosZA = .70) = 1.33 x 10^5
A(cosZA = .80) = 3.22 x 10^5
A(cosZA = .90) = 4.81 x 10^5
A few different fits:
Integrating over cosZA, using the first polynomial fit, the aperture at 10^17 eV for theta < 45 degrees is 7.60 x 10^5 m^2 sr. (See Mathematica calculation.) Using the third polynomial fit, the aperture is 7.36 x 10^5 m^2 sr.
The acceptance calculated previously from showers thrown using the LDF (see aperture plot) was about 5% at 10^17 eV. This covered a solid angle of Pi and an area of 4km^2, so it corresponds to an aperture of 6.3 x 10^5 m^2 sr.
