A keogram is a way of displaying the intensity of an auroral display over time. It creates a time-dependent graph by taking a narrow slice of a series of images recorded by a camera, more specifically and ideally a "whole sky camera". Keograms are usually created from a north-south oriented slice of the images, with north at the top in the Northern Hemisphere and south at the top in the Southern Hemisphere. This allows one to easily see the general activity of the display that night, interruptions by clouds, and the regions in which the aurora was seen in terms of latitude.