If you practice celestial navigation on land and do not live within sight of an ocean horizon you might use an artificial horizon, or you might use an aircraft sextant. Aircraft sextants are not as accurate as marine sextants but can work quite well. I find that the accuracy of my observations is improved by mounting my aircraft sextant to a tripod for improved stability.

This holder is for a US Bureau of Standards Type D aircraft sextant (in the unlikely event that you need a holder for one).