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It is of course incredible,
but it looks like those people who
designed SNO-T had Lunars in mind:-)
However no Russian book or manual I've seen ever mentions Lunars.
Consider the following features:

a) high quality inverting scope with cross-wires
(unique for modern sextants, and with larger objective lens
than those of the old ones).

b) the arc permitting to measure up to 140 degrees.
(so it is closer to a "pentant" than to a sextant).
I had no opportunity to try really large angles yet.

c) relatively light weight. Which probably makes it easier to
hold it in an inconvenient position.
If I understand correctly it is made of "duralumin",
a hard aluminium alloy invented in 1930-s for airplane
construction. According to the booklet of Hezzanith company,
(which apparently pioneered this meterial in sextants)
its stress resistance exceeds that of brass (="gun metal",
as Hezzanith calls it) by a factor of 2.

As a curiosity, I add the "reading microscope" typical for
very old sextants, but never found on the newer ones,
including other Russian models (am I correct?)
It has a usual "infinite" worm skrew with a reading drum as all
modern sextants, no nonius, but also the microscope to read the drum.
The microscope also illuminates the scale (but without batteries!)
and makes it easy to read to 0.1' even in complete darkness.

Alex.

   

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