Dear Global Surveyors,
I wondered whether you can help me with some advice. I live on the Gold Coast in Queensland.
I have an interest in celestial navigation.
The traditional instrument (the sextant) is limited by
(1) accuracy of about 10-15 seconds of arc in perfect conditions and
(2) the need to have both the horizon and stars visible at the same time (limiting sighting time to about half an hour of nautical twilight at dusk and dawn).
The real kings of modern accurate celestial navigation were not the sailors, but the soldiers in WWII in the desert campaigns.
With no navigational features (except the stars) in the desert and no GPS, these guys would get out their astronomical theodolite each night, and take a number of very accurate star sights.
From this data, they could derive quite an accurate fix on their position to within only a few meters !
They would then use dead reckoning from that point until the next celestial fix (the following night weather permitting).
Using the theodolite solved the abovementioned shortcomings of the sextant....
(1) their accuracy was generally of the order of 0.1-0.2 arc seconds for the two models typically used and
(2) their sophisticated leveling mechanisms obviated the need for a visible horizon (allowing sights to be taken any time the stars were visible)
Two Swiss companies were commissioned to make these astronomical theodolites....
Wild Heerbrugg AG, Switzerland with the T4 Universal Instrument and
Kern & Co. AG, Aarau, Switzerland with the DKM3A Astronomical Universal Instrument.
These are purely optical instruments, save for an illumination system for the readouts and levels.
These theodolites are quite rare nowadays and have become collectors items.
I have recently purchased a Kern DKM3A from Eastern Europe, which I think needs a good service.
The mechanical parts all seem to move well, but I can't get a clear picture through the viewfinder.
Part of the problem may be that I a not yet familiar with how to operate the instrument, but at the very least the main lens and mirror look like they needs a good clean and I wonder whether I can see some strands of fungus in there ?
I am in the process of trying to obtain operator's and service manuals, which did not come with the instrument.
My question for you is.....
Do you know anyone in Australia who would have any familiarity with such an instrument and would have the skills to service and calibrate/collimate it ?
If the main lens and/or mirror are shot, would it be possible to manufacture replacements if the specifications of the original glass is known (or could be measured from the existing parts) ?
I imagine the spare part situation for such an instrument is probably nonexistent.
The larger components (Striding and Horrebow levels, leveling trivet base etc.) occasionally come up on eBay, but I imagine the smaller components (like a lens or mirror) may be a bit hard (ie. impossible) to find.
I'm keen to get this instrument back to fully working condition if I can.
I have spoken (by email) with Urs at Swisstek.com (they seem like a relative authority on Kern and Wild instruments), who suggested I send the instrument to his contact in Switzerland, and this may well be the best option.
Shipping there and back will likely cost US$1000 (the instrument is fairly heavy, bulky and fragile), with additional costs for any repairs.
As you can understand, I would like not to have to go through this trouble and expense if it was possible to service and repair the instrument at home.
Any advice or contacts you could provide would be very welcome.
Thank You and Kind Regards
Richard McLean
