NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Instumental error?
From: Alexandre Eremenko
Date: 2005 Apr 21, 00:14 -0500
From: Alexandre Eremenko
Date: 2005 Apr 21, 00:14 -0500
In Soviet union we never believed any specifications:-) (The case we are discussing is even worse: My sextant was made in the year SU collapsed:-) But I am surprised that you trust so much what Celestaire or CP write in their advertising booklets. Or is it normal in the West that such things are trusted? Alex. On Thu, 21 Apr 2005, Bill wrote: > > Bill wrote: > > "> If I recall, the specs > >> are plus/minus 10 seconds error along the arc (0.17'). > >> Unless you got a > >> dud, any value higher than 0.2' is highly suspect. > > > > And Alex replied: > > "Yes, I'm afraid it is a dud." > > Frank responded: > > > > I don't buy it. That the certificate *says* the error is 10 seconds doesn't > > mean much of anything. Arc error is a correctable error and shooting > > lunars/star-star sights is probably the best way to detect it. Build your > > table, and > > then use it. And the fact that such error exists doesn't mean the instrument > > is a "dud". Correcting for arc error, once you have determined it, is every > > bit as easy as correcting for index error. > > Frank > > I was looking at the bigger picture (for a refreshing change of pace). > Celestaire, for example, speaks of accuracy by the lot. I would expect my > Atsra III B to be no worse than plus/minus 19" throughout the arc, maybe > better, despite any certificate. Any Cassens & Plath no worse than > plus/minus 9". Any SNO-T no worse than plus/minus 10". Those should be > upper limits. That is not to say lemons do not exist. > > I have no cause to believe Soviet military gear would have been substandard > (although not petite ;-) If I accurately recall the post, some sort of cel > nav contest was won by a Polish sailor with a SNO-T--a long run of .2' > within known positions. If any of the list members have more details about > this seagoing cel-nav superstar, I would love to read them. > > > I don't buy it. > > Too bad. I have a gut feeling Alex would be willing to sell it if the > "right" offer came along.Kidding aside, I believe him to be the sort > that will persevere and defeat any idiosyncrasies the SNO-T may posses. > > Bill >