For the new 490 pixel camera, all real images recorded are required to pass a three-fold pattern trigger. The cuts for the new 490 pixel camera are shown in the following table. Degrees are as projected onto the sky. Image Parameterisation Frac2 is the fraction of the total light in the top two tubes. The cut above thus excludes any images that consist of only two tubes.
Size is the sum of light in the image.
Max1 and Max2 are the values of the highest and second highest tubes, respectively. The cut on this above eliminates very small images. A single moun emits a cone of Cerenkov light. So a muon passing near to the axis of the camera will leave a ring shaped image. These images tend not to be very bright.