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    Re: Horizons and levels
    From: Doug Royer
    Date: 2003 Jul 15, 12:17 -0700

    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:Fred@ACF.ORG]
    Sent: Tuesday, July 15, 2003 11:29
    Subject: Re: Horizons and levels
    I'm interested in how close you can get at home with the MS-733.
    Routinely 0.2' or is it closer?
    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:Fred@acf.org
    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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