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I don't have TV at home and I am watching everything via youtube, skipping annoying ads.  However, one particular advertisement attracted my attention. It was an advertisement for seiko prospex wristwatch where a sextant came in the picture (see attachment). The man holding the sextant on his way to the North Pole is Naomi Uemura - Japanese explorer and navigator. I googled about him and found the following short article:  

Seiko VS Rolex: Duel at the North Pole — Seikology 

Interestingly, the sextant he is holding does not have an artificial bubble horizon which is supposed to be used in these conditions (see the foto attached) since the natural horizon is unreliable. I assume he was using his Rolex wrist watch as a chronometer (but how about very low temperatures?). I am pretty sure that more info about these details can be found in his book. If someone knows more, please comment.