NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: sight reduction with GPS receiver
From: Charles Seitz
Date: 2005 Mar 21, 21:54 -0500
From: Charles Seitz
Date: 2005 Mar 21, 21:54 -0500
Frank,
I looked into the instruction book for my
GPS 48 (Dated Dec 1999) and found over
100 datums listed.
GPS 48 (Dated Dec 1999) and found over
100 datums listed.
There are variations of NAD27 for all sorts
of North American places.
of North American places.
Some exotic Datums of local interest:
Adindan - Ethiopia, Mali, Senegal, Sudan
Easter Island 1967
DOS 1968 - Gizo Island
Viti Levu 1916 - Fiji Islands
Tristan Astro 1968 - Tristan da Cunha
Where's that?
Easter Island 1967
DOS 1968 - Gizo Island
Viti Levu 1916 - Fiji Islands
Tristan Astro 1968 - Tristan da Cunha
Where's that?
And of course:
WGS72, WGS84
I'm inclined to believe that the GPS 48 GC distance
is not a spherical earth calculation. However, the
test that you suggest is noteworthy. I'll do it.
--- CHAS
----- Original Message -----From: Frank ReedSent: Monday, March 21, 2005 20 14Subject: Re: sight reduction with GPS receiverChas you wrote:"If anyone cares to try a different GPS
receiver, be certain it is set for WGS84
and directions are reported with respect
to true north."What other options can you specify besides WGS84? (the only GPS receiver I own is an early basic model with no bells and whistles)By the way, I should have thought of this earlier, there is a simple test for ellipsoidal versus spherical distances. Set the device to calculate the distance between Lat,Lon of 0,0 and 0,90 (both points on the equator). Then calculate the distance between Lat,Lon 0,0 and 90,0 (along the Greenwich meridian to the North Pole). If the calculation is spherical, the distances will be the same.-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
