 Check out the bookstore at IRBS.com |
|
|
|
|||||
|
||||||
From: Royer, Doug (no email)
Date: Tue Jul 15 2003 - 17:59:45 EDT
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:]
Sent: Tuesday, July 15, 2003 12:53
To:
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:]
> 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
>
>
------------------------------------------------------------------------
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
|