Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Horizons and levels
    From: Fred Hebard
    Date: 2003 Jul 15, 15:52 -0400

    Doug,
    
    One other question.  Is the position obtained from sights on more than
    one object, or is this the average of Hc-Ho for one object, where Hc
    would be obtained using the known gps position?
    
    Thanks,
    
    Fred
    
    On Tuesday, Jul 15, 2003, at 15:17 US/Eastern, Royer, Doug wrote:
    
    > 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{at}ACF.ORG]
    > Sent: Tuesday, July 15, 2003 11:29
    > To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    > 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:Fred{at}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
    >
    >
    ------------------------------------------------------------------------
    Frederick V. Hebard, PhD                      Email: mailto:Fred{at}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
    
    
    

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site