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From: Royer, Doug (no email)
Date: Tue Jul 15 2003 - 15:17:55 EDT
Fred,let me explain all the variables in my statement.Useing both the liquid
and glass horizons and both the M-25 and MS-733 sextants.Both types of
horizons give me roughly the same results with both sextants.Useing the
Davis I always,always,average the sights useing at least 3 cuts and times
for each body.Doing so and painstakingly checking the sextant constantly for
error during each round I can get on average about 0.2 of a mile from my
known pos.Sometimes better,most times not.Useing the Tamaya and not
averageing the cuts and times(as I do most times takeing sights at sea due
to time or condition constraints)I on average get 0.2 mile from the known
gps pos.However,useing the 733,if the sights are averaged as above I get a
range from 0.2 mile to 40 ft. from the known gps pos.Most of the time
between 0.1 and 0.2 mile.That's roughly a 500 to 1,000 statute ft. average
useing the Tamaya.
-----Original Message-----
From: Fred Hebard [mailto:]
Sent: Tuesday, July 15, 2003 11:29
To:
Subject: Re: Horizons and levels
Doug,
I'm interested in how close you can get at home with the MS-733.
Routinely 0.2' or is it closer?
Thanks,
Fred
On Tuesday, Jul 15, 2003, at 14:11 US/Eastern, Royer, Doug wrote:
> Just want to get a couple of more ideas before I leave.I also want to
> explain what and why I did it.As for the 3 vs. 4 leveling bolts,maybe
> 3 are
> better or at least easier to use to level the reflective surface.It
> takes
> 45-90 sec. to level my horizon and can be frustrateing to get it
> level.It
> appears that with 3 bolts the leveling will be faster and just as
> good.The
> spirit levels I bought are round,the size of a 25 cent coin and have a
> circle inscribed or printed on the convex plastic lens a little
> smaller than
> the size of a dime.They only cost $2.50 each,so they aren't very
> accurate or
> I should say they can't give that fine of a reading.However,the little
> system that was made at least proves to me that this is a viable
> alternative
> to liquid levels.I leave it to you guys to hash out the finer details
> of
> makeing it more accurate.Once this thing,and the glass one I made, is
> leveled(relative)I can view all bodies untill they move so much as to
> need
> to reposition the horizon.The Sun and Moon were observed.Last week I
> observed the daytime Moon with the glass horizon I
> made.Spica,Arcturus,Deneb,Altair,Vega and Antares were observed.Last
> night I
> observed Nunki(with the glass horizon and the MS- 733) untill the
> light from
> the riseing Moon washed it out.The question is how accurately must it
> be
> leveled?I started building a horizon because of frustrations useing a
> Davis
> horizon in strong winds during backpacking trips.I use a Davis M-25
> plastic
> sextant on these trips and get an accuracy from the sextant as + -
> 0.2' at
> the very best.I'm just pleased as punch getting a fix within 0.5 mile
> of the
> gps pos. useing the above set-up.At home useing the above horizons and
> the
> MS-733 sextant I get finer results but that is to be expected.My main
> goal
> in this was to see if one can get good refections of stars or planets
> with a
> glass or plexiglas horizon,be fairly easy to use and be light in
> wieght.At
> least to me,these practical experiments prove it is all the above.
>
>
------------------------------------------------------------------------
Frederick V. Hebard, PhD Email: mailto:
Staff Pathologist, Meadowview Research Farms Web: http://www.acf.org
American Chestnut Foundation Phone: (276) 944-4631
14005 Glenbrook Ave. Fax: (276) 944-0934
Meadowview, VA 24361
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