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Latitude and Longitude

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not-my-real-name
(@not-my-real-name)
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How do you display latitude and longitude on a survey map. I am looking to do so, and I know these values are somewhat imprecise unless displayed to fractions of a second.

I did a little experiment in my CAD computer entering the values for latitude and longitude with differing precision. I am in NAD83 Massachusetts Mainland Zone for this test.

dwg

Historic boundaries and conservation efforts.

 
Posted : August 15, 2023 10:58 am
peter-lothian
(@peter-lothian)
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I've never plotted Lat-Long on a plan, just state plane coordinates. I vote for the 0.001" style, as it gets you to the precision where you can convert to SPC reliably to 0.01' representation.

 
Posted : August 15, 2023 11:09 am
not-my-real-name
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@peter-lothian 

I agree. My OPUS solution report has five decimal parts of a second.

Historic boundaries and conservation efforts.

 
Posted : August 15, 2023 11:16 am
rover83
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As a general rule, 0.0001 seconds ~ 0.01 feet of difference, at least around here.

I tend to follow the lead of the NGS and run things out to five decimal places for seconds.

 
Posted : August 15, 2023 11:16 am
MightyMoe
(@mightymoe)
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On a plat for a section corner tie I show .001” which is roughly 0.1’, really within .05’ because of rounding. Show epoch and understand that it’s an L,L,T number. 

 
Posted : August 15, 2023 11:27 am

bill93
(@bill93)
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Express it with the number of digits that are significant - the last digit is somewhat uncertain.

And be sure to give full metadata.

 
Posted : August 15, 2023 11:57 am
not-my-real-name
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Thank you everyone. I can only make my software display four decimal parts of a second. I display a chart on the map of the State Plane coordinates along with the latitude, longitude and metadata. 

Historic boundaries and conservation efforts.

 
Posted : August 15, 2023 12:01 pm
field-dog
(@field-dog)
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I can only make my software display four decimal parts of a second.

What software are you using?

 
Posted : August 15, 2023 4:01 pm
not-my-real-name
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I don't want this to become a discussion about which brand is better, however, I did find that using a different part of the software can get more decimal parts of one second in the latitude and longitude values.

Historic boundaries and conservation efforts.

 
Posted : August 15, 2023 6:13 pm