View your WinAstro shopping basket


You are here > Sextants > Astra
English (United Kingdom)

Astra Sextants

Astra sextants are manufactured in China as a brand name for Celestaire. They offer good value for money metal sextants - not as good as Freiberger and other high end sextants, but considerably more accurate than plastic ones.

Astra IIIB Sextant

Astra IIIB Sextant

The Astra IIIB is an all-aluminium sextant, and when introduced quickly became popular due to its low price compared to other models then on the market. Since then its specification has steadily been improved, and it continues to offer good value for money.

The sextant is fairly light with its aluminium frame and plastic handle. It has a good sized index mirror, and this index mirror is now silvered on the front face for maximum accuracy. There are 4 shades for the index mirror, and 3 for the horizon mirror. The sight scope is 3.5x40, with options for a protective rubber eyepiece, sight tube, and artificial horizon. There is LED illumination of the drum and limb, in case you don't have a torch to hand (needs 2 AA batteries). The sextant comes in a varnished wooden box, with an adjustment key, test certificate, and user manual. The manufacturer's stated accuracy is ±20" of arc.

Arm radius 153 mm Dimensions  
Scale -5° to 130° Weight 1.2 kg
Micrometer visual interval 0.2' Box dimensions  
Scope 3.5x40 Box weight 6.4 kg
Index mirror 56 x 42 mm
Horizon mirror 51 mm ø

 The sextant is available with either the traditional split horizon, or a full horizon.


Astra III Professional Sextant

Astra III professional sextant

This sextant is to the same design as the popular IIIB, but the primary change is that it has a bronze arc fused to an aluminium frame, similar to the Tamaya sextants. Other differences are that it has an improved handle design, and the light can be dimmed for when viewing faint stars. Bronze can be machined more accurately than aluminium, and is a more stable material, so the stated accuracy is improved to ±15" of arc. Also, and probably more importantly, many people find that the extra weight makes the sextant steadier when taking a sight.

Arm radius 153mm Dimensions  
Scale -5° to 130° Weight 1.4 kg
Micrometer gradation 0.2' Box dimensions  
Scope 3.5x40 Box weight 3.3 kg
Index mirror 56 x 42 mm
Horizon mirror 51 mm ø

 The sextant is available with either the traditional split horizon, or a full horizon.

Sight Tube

Astra sextant sight tubeWhilst the magnification obtained through having a scope instead of a plain sight tube can make your sights more accurate, there are times when a plain sight tube is an advantage. If you are a beginner, the much larger field of view makes it easier to identify the stars through the sextant; and if the boat is moving a lot a sight tube makes it easier to keep the body in view. It is also of benefit when taking horizontal sextant angles, as you can identify the landmarks and the magnification is not needed.

The sight tube fits both Astra sextants, as well as Cassens & Plath and Tamaya. It is made of blackplastic, and has a matt black interior to minimise refletions. It can take the optional rubber eye cap.

Practice Artificial Horizon

Astra sextant artificial horizonThis bubble horizon replaces the normal scope on the sextant, and allows you to take a sight without being able to view the horizon. It has zero magnification, like a sight scope, and as it is unlit it is not suited for use after twilight. Sight accuracy is claimed to be about 2'.

In use, you hold the sextant so that the horizon hairline on the right side of the scope lines up with the bubble on the left. You then change the sextant angle to bring the body down to the hairline. When you install the artificial horizon, you calibrate it, and include this offset in your sight corrections.


Rubber Eyecap

This rubber eyecap can be used with the scope, sight tube or artificial horizon.