GPS devices

APT is able talk with various GPS receiver devices sometime called "GPS dongles". All devices that can talk NMEA protocol and expose a COM port are supported. Also there are various Android and iOS apps than export the smartphone's location as NMEA device via Bluetooth.
See the section Extra Devices for information how to configure the connection to a GPS dongle.
The coordinates from a GPS dongle is used by by the mount, for the Darkness Clock and DSD Calculator.