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    Re: Freiberger sextant with prism
    From: Martin Lechler
    Date: 2022 May 23, 16:45 -0700

    Hi Paul,

    Thank you or posting the certificate! This is the first time I have seen an East German military one. It actually gives a lot of clues about the sextant's original use (I don't know if you are from Germany or read German - please accept my apologies if the following is already quite obvious to you):

    The certificate has been issued on February 6, 1978, by the Office No. 10 for the Inspection of Navigation Technology (Prüfstelle für Schiffsführungstechnologie Nr. 10) of the People's Navy of the National People's Army (Nationale Volksarmee - Volksmarine), the armed forces of the German Democratic Republic. The entry "SHD" in the line at the top that usually would contain a ship's/boat's construction number (Schiff/Boot-Bau-Nr.) indicates that the sextant was not issued to a specific ship, but to the Maritime Hydrographic Service of the GDR (Seehydrographischer Dienst der DDR), which was a separate unit of the People's Navy, directly  subordinated to the latter's overall commander. Among the main responsibilites of the SHD were buoyage and nautical charts. See https://de.wikipedia.org/wiki/Seehydrographischer_Dienst_der_DDR for the SHD and https://de.wikipedia.org/wiki/Liste_der_Schiffe_der_Nationalen_Volksarmee#Seehydrographischer_Dienst for vessels on which the sextant might have been employed.The certificate is signed by a civilian employee who had the surname "Merker" if I read correctly.

    The serial numbers given on the certificate and on your sextant differ by a count of only four. It is possible that your sextant belonged to a batch of surveying sextants provided to the SHD that had continuous serial numbers. As the East German bureaucracy, and especially that of the NVA, was known for scrupulousness if not nitpicking, it is most likely that originally separate certificates matching the serial numbers had been issued and that the certificates got mixed up only at a later stage or that the certificate matching your sextant was lost and substituted for by another one from the same batch later when the certificates didn't matter anymore. The different type of certificate issued for sextants in civilian use was valid for three years; if the same is true for this type of military certificate, it would have been the second certficate issued for the sextant, which was produced in 1974 as indicated by the first two digits of its serial number. I don't know whether the GDR navy accepted the original manufacturer's certificate for the first three years of the sextant's use, or whether the sextant had to be tested by the military inspection office right away when it entered navy service, even when it was brand-new. The lack of a later certificate might indicate that the requirement for regular re-certification had been suspended by that time, or that the sextant was not in use anymore.

    In any case, notwithstanding the slight difference in the serial number on the certificate, it seems certain that your sextant was issued to the Marititme Hydrographic Service of the GDR's navy and was intended to be used for its surveying mission on different vessels (maybe with a secondary use in navigation, as implied by the option to swap the pentaprism for horizon shades). Given the "as new" condition in which you acquired it, it is an open question whether it was ever actually used. Your sextant might have been surplus stock, or in the mid-1970s other surveying means, including electronic ones, had already started to make sextants obsolete.

    Another intriguing question relates to the correction values "due to excentricity of the instrument" found on your certificate. Today, Freiberger sells their (otherwise identical) drum sextants in three quality grades: Sextants with correction values of not more than +/-20 arcseconds are sold under the promotional label "Sirius" for a higher price; the standard-grade drum sextants have at least one correction value in excess of +/-20 arcseconds, but none exceeding +/-40 arcseconds; while sextants with higher correction values (but I believe still none exceeding +/-60 degrees) are not available through regular distribution channels but sold at the factory with a discount on special demand. I believe it has been this way since 1990 or shortly thereafter. After looking at lots of certficates of second-hand Freiberger sextants offered through different channels, I have got the impression, currently still unconfirmed (others here with more experience might be able to chime in), that prior to German unification, a similar type of grading was in place for Freiberger drum sextants: Drum sextants with correction values below 20 arcseconds were given a factory certificate (Werksattest) stating exact correction values up to the last digit and exported to Western countries, thus contributing to the acquisition of hard currency by the GDR. Drum sextants with correction values upt to 60 arcseconds went to the domestic merchant navy and other civilian users with a test certificate (Prüfschein) issued by Freiberger on behalf of the GDR Ship Revision and Classification authority (DDR-Schiffs-Revision und -Klassifikation, DSRK), which stated correction values in multiples of ten. Your certificate might now suggest that drum sextants with intermediate-grade correction values (maybe above 20, but below 40 arcseconds?) were destined for the GDR navy, with military certificates stating correction values in multiples of five. In the GDR, it was standard practice that higher-quality products went into export to generate much-needed foreign currency, while domestic users had to content themselves with lower-grade goods, though the military would have been given preference. By the way, private citizens in the GDR seem not to have been able to purchase sextants at all.

    In any case, you are to be congratulated on your purchase. 311 euros (at a regular eBay auction?) is a very good price even for a regular Freiberger drum sextant and a true bargain for the extremly rare pentaprism version. When you received the sextant, did all moving parts, including the drum release, move freely without too much resistance? The grease in Freiberger sextants of this age tends to gum up, especially if not regularly used.

    As for practical use cases apart from surveying, I wonder whether it would be possible to employ the pentaprism to take "over the shoulder" sights? For example, if a body is at a height of 40 degrees in the south but a shoreline obscures the horizon, while the horizon in the north is clearly visible: could the sextant with the pentaprism in this case be used to measure the body at 140 degrees from the northern horizon? 

    Regards, Martin

       
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