Though I used a GPS unit to set lat/long position. The Nook doesn't have GPS nor can it be trangulated as it doesn't speak cellphone. That leaves Google's service which attempts to determine position from the WiFi IP address (my Grand Rapids DSL service homes with Earthlink via Kalamazoo -- how accurate can THAT location service be?).
I've seen one app in the Nook STore. can't recall the name. Sky something perhaps.
If you search for some of the bigger app names then you can find it in store. Make sure to add 'app'.
'night sky app'
It should show up.
Else you can get from Google Play Store.
Which app were you trying to enter location in?