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Patrick,

I'm glad to hear that tectonic forces are not too aggressive in the
vicinity of your garden.  I'm at about the same latitude, but 81* 50'
W, and found out the same thing about the deck attached to the back
of my house, much to relief of my family!

I didn't work through all your sheet, but your assumed longitude for
the first sight is 76* 7.2' W when the GHA would suggest that 62* 7.2
W is correct.

I started out with HO 229, but then moved to computerized reduction
to focus on my sextant technique.  By the time I had the technique
down, I was too lazy to go back to hand calculations!

One thing I did find was that accurate timing, to the second, is
critical. I used the difference between the observed altitude and the
calculated altitude as a metric of accuracy.

Fred


On Jan 30, 2011, at 7:40 PM, Patrick Goold wrote:

> Dear Nav-listers,
> This is boring compared to recent lunar observations, but I am
> still trying to determine the position of my front garden using sun
> sights.  As advised by several of you, I moved past using meridian
> passage.  On Saturday I took three sights one approximately an hour
> before LAN, one at LAN and one approximately one hour after.  I
> then reduced the sights using H.O. 229 (which I discovered is a lot
> like doing your taxes) and plotted the results on a universal
> plotting sheet.  The plot showed that the altitude intercepts of
> the second and third sight intersected at a point very close to my
> GPS long/lat.  The first one, however, seemed out.  I ran my data
> through the on-line sight reduction calculator at  www.celnav.de/sightred.htm> and it confirmed the problem.  I cannot
> find my mistake.  Worksheet attached.  All assistance gratefully
> received.
>
> BTW, the garden is, relatively speaking, stationary.
>
> Best regards,
> Patrick
>
>
> Charles Olson: "Love the World -- and stay inside it."
>
> <29 Jan sunsights.pdf>

   

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