[AZ-Observing] Re: Cherry Road Site - Lat and Long?
- From: Rick Tejera <saguaroastro@xxxxxxx>
- To: "az-observing@xxxxxxxxxxxxx" <az-observing@xxxxxxxxxxxxx>
- Date: Wed, 30 Jun 2010 17:39:14 -0700
A little search on wikipedia turned this up in the article on google maps:
Hide Map projection
Google Maps is based on a close variant of theMercator projection. If the earth
were perfectly spherical, the projection would be the same as the Mercator.
Google Maps uses the formulæ for the spherical Mercator, but the coordinates
of features on Google Maps are the GPS coordinates based on the WGS 84 datum.
The difference between a sphere and the WGS 84 ellipsoid causes the resultant
projection not to be precisely conformal. The discrepancy is meaningless at the
global scale but causes maps of local areas to deviate slightly from true
ellipsoidal Mercator maps at the same scale.
Sent from my iPod
Rick Tejera
Editor, SACnews
Saguaro Astronomy Club
www.saguaroastro.org
K7TEJ
On Jun 30, 2010, at 17:15, Rick Tejera <saguaroastro@xxxxxxx> wrote:
> The default datum on nearly all GPS units is WGS84. When I took measurement
> the EPE was less than 15 feet.
>
> When I punch in what I got into Google maps it put the mark right where I set
> up.
>
> Now punch in my address. And it's in the middle of the street two houses down.
>
> Not really sure that the datum is the issue.
>
> Sent from my iPod
> Rick Tejera
> Editor, SACnews
> Saguaro Astronomy Club
> www.saguaroastro.org
> K7TEJ
>
> On Jun 30, 2010, at 16:57, Victor Herrero <hubbleed@xxxxxxxxx> wrote:
>
>
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