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Subject: Re: ANWR
From: Dan Dugan <>
Date: Mon, 20 Jun 2005 00:37:49 -0700
Bill Rainey, thanks for your reply:

>The other parameter you want to report to the park is the map
>datum you used. U.S. Topo maps are still commonly NAD 27
>CONUS (North American Datum ...Continental United States). My
>impression is at least GPS units sold in the US default to
>another datum (WGS 84), altho you can set them to convert
>screen output to NAD27 CONUS or many others.

Huh. A different reference point? They've moved Greenwich, or 
something? How far off are you in the wrong system?

>Consumer GPS units can sometimes produce startlingly bad
>short term fixes, so a reality check via map software (e.g.,
>National Geographic's Topo or several others) at the position
>you are about to report is usually educational.

I have TOPO, and plan to hook up a GPS to it. I'm looking for one 
that's compatible with the Mac (USB) so I don't have to use a serial 
port dongle thing.

>The dominant GIS software parks use to map location data
>'expects' decimal degrees as input, though conversion is not a
>big deal (assuming the datum is known).




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