Design and construction of a portable high resolution positioner using star patterns

Today positioning and finding the direction of true North has a significant role in our life. In these days GPS has presented a complete answer to the problem. But sometimes our access to the communication systems will be limited. In this situation what should we do? We present a method using star patterns to obtain our position (longitude and latitude) and the North direction with an accuracy of about half an arcminute. For the accuracy, some corrections like the refractive index of the atmosphere, relativistic aberration and some other cases were considered in spherical geometry of the sky. The exposure time of the photograph of the sky is 0.50 s. With these considerations, we obtained accuracies of 0.503 ′ (932 m) in latitude, and 0.816 ′ (1510 m) in longitude and North direction. Among the main goals of the design were a reasonable price and portability of the instrument, which is completely achieved.