What crosshairs were used to maintain an attitude during the famous manual trajectory correction burn during Apollo 13's return to Earth? What was their normal function?
This is all I can hear in the reenactment in the Apollo 13 movie:
Well Houston we’ve got one. If we can keep the Earth in the window flying manually, the (coax??) crosshairs right on its terminator, all I need to know is how long I need to burn the engine.