| Description: The emission_angle element provides the value of the angle between the surface normal vector at the intercept point and a vector from the intercept point to the spacecraft. The emission_angle varies from 0 degrees when the spacecraft is viewing the subspacecraft point (nadir viewing) to 90 degrees when the intercept is tangent to the surface of the target body. Thus, higher values of emission_angle indicate more oblique viewing of the target. For ring data, values in the range of 90 to 180 degrees indicate viewing on the unlit side from oblique or edge-on at 90 degrees to the unlit nadir at 180 degrees. |