All-sky camera acquires images through so called fish-eye lense. The
lense covers the whole sky but distorts the spatial scales so that auroral
structures in the middle of picture are systematically larger than those
near the horizon (c.f. the image on the convex side of a tea spoon).
In the round field-of-view of the camera north is at the top and east
at the right edge of the image. If the sky is overcast even detecting
the round field-of-view from the black background can be difficult. The
Moon is occasionally visible in the images as a bright stable spot, and
should not be confused with auroras.