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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Horizons and levels
From: Doug Royer
Date: 2003 Jul 15, 14:59 -0700
From: Doug Royer
Date: 2003 Jul 15, 14:59 -0700
Fred,I like doing multiple object fixes.Usually 3 differant bodies per round.Sometimes an advance combined with 1 or more bodies.Sometimes a single body over a period of many hours.Sometimes I move to other geographic positions not wanting to know its coordinates,use an AP,reduce the sights,get a fix and then check it against the gps coordinates.Sometimes I use sight reduction books,especially in the above procedure.If I know the coordinates of a pos,like home,I will treat it as an EP and use the sin-cos method with a Casio fx-6300 calculator or a Visor handheld with reduction software.While backpacking I will average the track travelled(relatively)to find the DR then reduce the pos for comparison or find the gps pos 1st then reduce the sights from that.--Original Message----- From: Fred Hebard [mailto:Fred@ACF.ORG] Sent: Tuesday, July 15, 2003 12:53 To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM Subject: Re: Horizons and levels 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@ACF.ORG] > Sent: Tuesday, July 15, 2003 11:29 > To: NAVIGATION-L@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@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@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