If this is 2d, then the simplest solution would be to check if GO’s current position is in the range of a rectangle that your camera is now showing - you know its borders, because you have the camera position and its range.
In general this problem is called “culling”, you can search for it, there’s a lot of solutions. There is also this thread on the forum 
Oh, there is also this thread, but I don’t know what is the progress?