Error is 0.05 at the equator. Value is actually diameter of a circle with an area equivalent to the crater's. We measured the area digitally by outlining the rim and counting the number of enclosed pixels. For craters with terracing, the rim is defined by the outermost boundary of the observable terraces. In most cases the end result is nearly the same.
Value is the density of craters in the neighborhood of the specified crater.
A representative location in the crater floor is similar in brightness to the majority of the crater floor. A representative location in the terrain surrounding the crater is a piece of terrain near the crater that is similar in character to the terrain that the crater formed on but that is unaffected by the crater. Within the crater we chose a piece of floor that appeared to be similar in brightness to the majority of the floor material. The average DN is the average of the logarithm of the backscatter at each pixel location. This does not include ejecta that was obviously emplaced as long run-out flows.