Mirrors Sextant mirrors have a limited lifetime before needing resilvering or replacement. Estimates range from 2 to 6 years in marine service. While resilvering is an option, good quality is hard to achieve. New mirrors are not much more expensive, and are shown below.

Horizon Mirrors
Astra IIIB – 51mm diameter with mirror frame
Traditional (half silvered) #0504R
Whole Horizon #0503R

Other sextants (Cassens & Plath, C. Plath, Tamaya, Freiberger) 57mm, frame not included
Traditional (half silvered) #0703

Index Mirrors (56 x 42mm)
Astra IIIB no frame #0517D
Astra IIIB with frame #0516D
Other sextants no frame #0517D

The 3.5 x 40 scope supplied with the Astra IIIB has become a Universal Scope, and has been sold with Cassens & Plath, C. Plath and Tamaya sextants. To determine the fit on other sextants use the diagram shown below. (NSN 6605-012533442)

Universal Telescope #0508

To determine the fit on another sextant, the ends of the fork from its regular scope should approximately match the outlines to the right.forkends

Replacement Parts

Spring Clip


Sextant Accessories

Universal Telescope


Replacement Parts

Index Mirror with Frame


Replacement Parts

Index Mirror with NO Frame


Replacement Parts

Mirror Adjustment Wrench