A digital read-out day and night marine sextant

TLDR: In this paper, a new digital read-out marine sextant was proposed, which can be operated in the day and during the night with light illumination as low as starlight.

Abstract: The Naval Ordnance Laboratory has under development and feasibility study a new digital read-out marine sextant which can be operated in the day and during the night with light illumination as low as starlight. The traditional marine sextant, which has been essentially the same design since the 18th Century, has been altered completely retaining only the index mirror and horizon principle. Using a lightweight, rugged rectangular frame the index mirror upon the frame is turned by an accurate gear train that controls mechanical counter which reads in degrees, 0.1, 0.01, and 0.001 degrees. The optical or replacement night vision image intensification telescope is inserted coaxially into the frame. Dual knobs on each side of the index mirror housing allows the sextant to be operated equally well by a right-handed or left-handed observer. The new sextant will be easier to read, less prone to reading error, lighter in weight, better balanced than the traditional sextant, and it is expected to have an accuracy of 10 arc-seconds. The digital read-out capability of the new sextant may eventually lead to remote read-out of altitude and time and automatic computation of ship's position. A pilot model of the new sextant has been constructed for shore and sea evaluation.