Hand-held sextant

Like the mural quadrant and the hand-held quadrant, in the past the hand-held sextant was one of the instruments most widely used by astronomers for determining the positions of the stars in order to produce highly detailed celestial maps. The measures were often used for calculating the positions of the brightest stars at a certain hour on a given day. The data were then published annually in summary tables, called ephemerides. Used also by navigators, ephemerides made it possible to identify the stars that were visible in the sky and to use these to calculate their position at sea.