Quintant

A quintant is a reflecting instrument like a sextant but with an arc of 144 degrees, measuring angles up to 144 degrees by the double-reflection principle, against the sextant’s 60-degree arc reading to 120 degrees. The larger arc let observers measure wider angles, such as horizontal sextant angles for a three-point fix or large celestial separations. The family (octant 45 degrees, sextant 60 degrees, quintant 72 degrees physical arc) is named by the fraction of a circle in the physical frame, not the angle read.