This application has many problems. If theres no GPS signal, it doesnt start (unless one goes to preferences and disable GPS, and manually enters coordinates). The manual coordinates cannot be filled in from the GPS, why not ? There is no count down timer until a pass (why not ?). There is no precise clock display (with seconds), why not ? The application has crashed many times on my latest 3GS 3.1.3 iPhone. This app would be OK if it was free, but not for a paying app ! Stay away from it. Better off by directly bookmarking heavens-above in Safari !