[Cdt-l] Ley map datum?

[Jonathan Ley]

The compass rose points are WGS 84... all pulled from outside sources, 
and manually aligned with points on the maps.

Anyway, a few hundred feet of accuracy isn't going to matter for the 
compass rose method. You should not need (or expect) any more than ~1/4 
mile accuracy if you're using that method. It's just to figure out 
"about where you are" on the maps... after doing that, you can just use 
cerebral navigational techniques to determine a more accurate location.

-Jonathan


On 4/13/2013 5:28 PM, bcss at bresnan.net wrote:
> Jonathan's maps are reproductions of USGS Topo sheets which were projected
> in NAD27 (North American Datum of 1927).  The NAD27 coordinate system
> disagrees with WGS84 (World Geodetic System of 1984 - the native language of
> gps) by up to 150'. Differences of 100' are normal. If you used a WGS84
> background map to calibrate a NAD27 map image, expect errors in that range.
>
>
>
> best wishes,
>
> Jerry Brown
> (970) 403-3527    Cell: (970) 749-0496
> mailto:bcss at bresnan.net
> www.bearcreeksurvey.com
>
> -----Original Message-----
> From: cdt-l-bounces at backcountry.net [mailto:cdt-l-bounces at backcountry.net]
> On Behalf Of Bob Bankhead
> Sent: Saturday, April 13, 2013 4:59 PM
> To: 'Bob Sartini'; 'Richard Lowery'
> Cc: cdt-l at backcountry.net
> Subject: Re: [Cdt-l] Ley map datum?
>
> The National Geodetic Survey defines a geodetic datum as "a set of constants
> specifying the coordinate system used for geodetic control, i.e., for
> calculating the coordinates of points on the earth."
>
> Basically, it defines how the GPS coordinates are determined. Hence the
> terms NAD 1927, NAD 1983, and WGS 84.
>
> For more than you'd ever want to know, go to:
>
> http (colon)//staff(dot)bcc(dot)edu/mzamkoto/ppt_gis/Datums(dot)pdf
>
> -----Original Message-----
> From: cdt-l-bounces at backcountry.net [mailto:cdt-l-bounces at backcountry.net]
> On Behalf Of Bob Sartini
> Sent: Saturday, April 13, 2013 3:29 PM
> To: Richard Lowery
> Cc: cdt-l at backcountry.net
> Subject: Re: [Cdt-l] Ley map datum?
>
> Does anyone know what datum means?
>
> On Sat, Apr 13, 2013 at 6:26 PM, Richard Lowery <rlowery2007 at yahoo.com>
> wrote:
>> Does anyone know what the datum is for the Ley maps?
>>
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>
>
> --
> Everything is in Walking Distance
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