This project involves the use of celestial measurements in order to predict the latitude, longitude and heading of the observer. The objective of the project is to assess whether a new inclinometer model and calibration procedure can significantly enhance the quality of navigation data acquired by the sensor suite. The suite consists of an Applied Geomechanics Tuff-Tilt digital biaxial inclinometer and a Sinclair Interplanetary SS-411 digital sun-sensor. The project will focus on the typical sources of error in an inclinometer and present a lab calibration method to enhance its performance. The sensor suite will also be calibrated together as a unit using a GPS receiver for time and geolocation data and a sun ephemeris as a measure of truth. Results from these tests are also presented.