This app does astronomical calculations. Among other things, sunrise and sunset will be muted at any point on Earth on a selected date. The position is either determined by the current location or can be selected by an entry. Determining the position is switched on with the "Determine position" switch. Below this, the accuracy of the position is selected. With "exact" the location is determined by the GPS. The astronomical sunrise and sunset is important when observing stars. Because within this time no sunbeam disturbs the star observations.