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Re: Sextants and Glue [was Sisteco Prismatic Compass]
From: Doug Royer
Date: 2004 Mar 24, 09:51 -0800
From: Doug Royer
Date: 2004 Mar 24, 09:51 -0800
Outstanding news on your C+P Fred.I also was looking at the moon's cresant and Venus for some time last evening.Beautiful wasn't it.Simply stunning at least from where I was. Is the horizon mirror(and index mirror for that matter)on your Huson the old style small mirrors?I'm not familiar with these old British sextants and am just curious.What year was it manufactured?Is it a vernier or tangent screw type?How "good" are the optics compared with others?Does it have the collar that the tube screws into(as in the old David White Mk.IIIs)or does the optic assembly fit into a screw on the frame? Just curious. -----Original Message----- From: Navigation Mailing List [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of Fred Hebard Sent: Tuesday, March 23, 2004 20:03 To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM Subject: Re: Sextants and Glue [was Sisteco Prismatic Compass] Well, the old C+P I got might be an OK instrument! I took two sights tonight, of Jupiter & Sirius and Ho-Hc for three replications of each was 0.042896+/-0.308899, and -0.07455+/-0.212369, where the error figure is the square root of the mean of (Ho-Hc) squared; since Hc is a parametric mean, the degrees of freedom should equal the number of replications. I've never gotten so close previously, although the standard deviations leave a bit to be desired. Ten to thirty more shots and I might get a fair idea of how good this sextant is. I was driving west and north for a few hundred miles this evening and the new moon was hanging about 15-20 degrees underneath Venus. It was perfectly clear and still and would have been a beautiful lunar, easy to shoot. Of course when I got home, the low western sky had clouded over. I have a fair amount of data for my Husun now, which I may get a chance to share with the list. It appears to need about 25 seconds of arc added to the existing corrections, although there's some additional periodicity in the errors which I don't know how to handle, having never fit such data. I still need to get a chance to fool around a bit with the data first. It would help also if I broke down and got the Husun's horizon mirror resilvered.