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# One thousandth of a minute?

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I'm trying to 'track down' a 'small bit' of information. Since the coordinates on the cache web pages are given in degrees and minutes (to 3 decimals), I was wondering how far a hundredth and a thousandth of a minute is around Sacramento (38.6 degrees north). I did some calculations assuming the earth is a sphere with a circumference of 24,900 miles. I came up with...

0.01' of latitude = 61 feet

0.001' of latitude = 6.1 feet

and

0.01' of longitude = 48 feet

0.001' of longitude = 4.8 feet

Is this correct? I realize this isn't exactly a GPS Unit or software questions, but I wasn't sure where else to post it.

Glenn95630

Think about the globe and it's lat/lon lines (not a map, but a globe). The Longitude lines that span north pole to south pole (and tell you your east-west position) get closer as they get nearer the pole, eventually intersecting. Latitude lines that circle the globe east-west and tell you your north-south position are much more uniform.

Here's a chart that arffer posted that will tell you just how far it is between degrees and decimals or portions, etc., at any given latitude.

That looks about correct. The GPS uses an elipsoid instead of a sphere but your calculations seem like a pretty good estimate. If you like you could down load a little freebie application from Mentor Software called foward inverse. Heres a link: http://www.mentorsoftwareinc.com/PRODUCTS/FWDINV.HTM

I have used the program and find it pretty useful. Give it a try. You can figure out distance for your Thousand of a minute pretty accurate here. The program support many formats and Datums.

mcb

Looks to me like your figures are as good as you can measure!

Oh! BTW, .001 minute of latitude is pretty much always equal to 6.1 feet all over the globe. I know there is an extremely small variance due to elipsoid, but too small to measure my most folks. The longitude is what changes by latitude.

I'm sure you all have this bookmarked, but there is a nice foot to mile/nautical mile/meter/everything else conversion tool found here:

http://www.onlineconversion.com/length.htm

Oh, btw - great table, Markwell! :^)

quote:
Originally posted by Pote:

Oh, btw - great table, Markwell! :^)

Thanks - but not mine. Arffer was the one that posted it (he and I seem to be running into each other a lot lately, but no one ever seems to see us at the same time...)

Which can effectively make 0.001' at that Lat of 7.7'

Cheers, Kerry.

[This message has been edited by Kerry (edited 09 September 2001).]

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