Astra IIIB Deluxe Sextant with Traditional MirrorView all products in Sextants #:  28019
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Astra IIIB Deluxe Sextant with Traditional Mirror

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The Celestaire Astra IIIB has somewhat revolutionized celestial navigation with such a high quality, accurate metal sextant available at such a good price.
More Details...   #28019
Brand:  Celestaire
MFG Part#:   0502D
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Astra IIIB Deluxe Sextant with Traditional Mirror 0502D

The Astra IIIB Sextant has revolutionized celestial navigation. Never before has such a high quality, accurate metal sextant been available at such a price.
Over 26,000 of the IIIB model have been sold in the US since being introduced in 1986; far more than any other serious sextant. Its popularity has spread through the rest of the world, making it the most recognized (and supported) Sextant worldwide.

Its low price, excellent optics, makes it the perfect selection for beginners. Yet, Celestaire know of several professional navigators who prefer the Astra IIIB merely because they can leave their expensive models at home without sacrificing any noticeable accuracy. 

Construction Details

The frame is made from a lightweight aluminum alloy which resists corrosion. Aluminum alloy is not new to sextant construction. It has long been used by many manufacturers for lightweight versions of their heavier brass or bronze sextants in order to reduce arm fatigue and unsteadiness among infrequent users. The sextant is electrically lighted by an LED on the Arc and Drum.

The Astra IIIB is considered by many to be the easiest sextant to use. Its lightweight and excellent balance makes it a pleasure to hold and makes sights easier to take under dynamic weather and sea conditions. Even reading the sextant is easier under low light conditions by having white degree marks against a black background as opposed to scribe marks on a brass Arc.

The Index Mirror is rectangular in shape and is the same size as used on more expensive Sextants. This shape allows more aspect of the mirror to be available for high angle sights. This means the Sextant does not have to be held as steady for them.

We are impressed with the degree to which each component of the sextant is tested. Each mirror and shade glass is tested for perfect flatness by the Fresnel diffraction pattern method. The Sextants are assembled and tested in a clean, professional, environment. Random units have been tested by Celestaire and several professional navigators, with results that rival the most expensive German and Japanese models.


The ability to quickly and economically change the type of horizon mirror is an attraction of this sextant to many navigators. This is because whole horizon mirrors are generally preferred by beginners who later may wish to change to a traditional mirror as proficiency is attained.

Maintainability is appreciated by schools and other groups who because of heavy usage need inexpensive replacement parts due to the threat of student mishandling.

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 an instruction book, certificate of accuracy, and adjusting wrench. 

Case external dimensions are 6.5"x 13" x 11". It includes a 3.5 x 40 Monocular telescope as standard equipment.

  Selecting a Marine Sextant


Arc -5° + 130°, radius 153mm
Accuracy ± 20″, throughout the arc
Micrometer Drum 1′ scale, vernier to 0.1′
Horizon Mirror 51 mm diameter
Index Mirrors 56 x 42mm
Shades 4 Index - 3 Horizon
Weight 2 lbs., 10 oz

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Q. Do you offer Free Shipping?
A. We have free ground shipping via UPS or Canada Post within Canada on most orders of $99 or more (pre-tax).

Q. What do you mean by most orders?
A. Some items are exempt from this offer and are indicated on the product page. Exempt items are usually bulky or heavy items such as buoys. Over 98% of the items on qualify for the free shipping offer.
To see what your shipping charge (if any) will be you can add the item(s) and quantities to the shopping cart and you will see a shipping cost calculator

Q. Where do you ship from?
A. We ship from Halifax, NS

Q. What is the delivery time?
A.  NS, NB, PE: 1 - 2 business days,
      ON, QC, NL: 2- 4 business days
      MB, SK, AB: 4-5 business days
      BC: 5-7 business days
When your order ships you will be emailed a tracking number which will give you the scheduled delivery date

Q. Do you offer Express Shipping?
A. We offer Express Shipping on some orders depending on the items ordered and the delivery address. If Express shipping is available for your order you will see the option on the checkout page. If you do not see the Express option and you want Express shipping please send an email and we will provide you with a quote (

Q. Do you require a signature on delivery?
A. We sometimes add a signature requirement especially if it is a high value package

Please Note:
Very Remote areas are exempt from Free Shipping offer. These are typically remote northern areas. Nunavut as well as many parts of the Yukon and NWT are exempt from free shipping

Money Back Guarantee
Guarantee You may return your purchase to us (with a return authorization number - use this form) within 30 days and we will refund the purchase price of the product. Items which are cut to order (rope, wire etc), software, chart cards and printed materials (paper charts, books) are not returnable.

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