Or whatever its called. It gives the angle away from the selected object. My only problem so far is sometimes sky safari pro 5 will not let me select another object by touch, so I have to go to search. It get locked on the object sometimes and wont let go via touch. Im using an iPad 3 mini. Maybe theres a trick or way to easily deselect an object. Ill have to study and read up more on that. Its about the only bug Ive noticed. Im using this with an evolution mount and enjoy the features with the Celestron evolution mount. A pretty nice combination.