Just as the Astra IIIB Deluxe sextant has become world famous as the premier low cost metal sextant, the Astra III Professional sextant with its low cost, high accuracy, and excellent handling qualities is destined to be the standard for professional seamen.
Its construction is similar to the Tamaya sextants in that it has a bronze arc fused to an aluminum frame. The bronze arc can be manufactured to a higher tolerance than aluminum, which gives the sextant higher accuracy. At the same time the aluminum frame keeps the over-all weight low enough that fatigue is not a problem as with a solid bronze or brass sextant. Nevertheless, the additional weight of the bronze arc adds about 8 oz. and gives the instrument an excellent balance and “heft”.
The handle is a new more comfortable design, and has an electrical outlet suitable for powering accessories. Except for the weight difference, accuracy, and handle improvement, it is exactly the same sextant as the basic Astra IIIB, and has all the attributes of it. These include thoroughly tested mirrors, maintainability, and the ability to quickly and economically change the horizon mirror type.
Included and Optional Equipment
The sextant has LED lighting of the arc and drum powered by two standard size AA batteries (not included) which install in the handle. It comes in a varnished wooden case, with instruction book, certificate of accuracy, and adjusting wrench. Case external dimensions are 6.5 x 13 x 11 inches. It includes a 3.5×40 monocular telescope as standard equipment.
Optional accessories include a 7×35 prism telescope, a Slip-on rubber eyecup for use while wearing glasses, and a Zero-magnification sight tube. A Practice bubble horizon and a Professional bubble horizon are available which facilitates effective practice without the need for a sea horizon. Although the sextant comes with a choice of either whole horizon mirror or traditional split horizon mirror, an extra mirror of either kind is available at nominal cost, and comes already mounted in its frame. Changing mirrors is done quickly by means of two easily manipulated screws.