Port - Manuall set the GPS reciever port.

Baud - Manually set the GPS receiver baud rate.

Refer to your device's documentation to find the correct port and baud rates.

AutoDetect - attempt to detect the GPS receiver connected to your device. If you are using a bluetooth GPS ensure it is switched on and bound first.

Start - start GPS receiver.

Stop - stops GPS receiver.

Slave Heading - select this to slave the horizon view to the GPS heading so that you can see what is in the sky directly ahead.

Sync System Time - Accurate times are important in astronomy. NightSky allows you to syncronise your PDA's time with the GPS atomic clocks.