I have been provided with Lat/Long coordinates from a reference station recorded in 1969. When I plot the coordinates into Google Earth the location appears to be out by c.100m. Is this due to the accuracy of the navigation at the time? If so can anyone recommend a way of estimating the equivalent coordinates using GPS available today?

The position in question was in Aberdeen.

The coordinate position was provided as thus: 57 08.95'N; 2 05.68'W.

There was a location sketch which when compared to Goolge Image was out by c.100m.

So if I transform from say ED50 to WGS84 I might be on the right track?

  • would those coordinates have been based on NAD27? If so, could they be plotted in say QGIS using EPSG:4267 then re-projected to NAD83? – DPSSpatial Jun 15 '15 at 16:53
  • 1
    you could do a quick test with this website. enter your points as nad27 and convert to wgs84 to see how they look. tagis.dep.wv.gov/convert – mr.adam Jun 15 '15 at 16:58
  • 2
    Where's the point? That can help us suggest which datum it may be using, and what transformation to use to convert it to WGS84 (or something else). – mkennedy Jun 15 '15 at 17:02
  • @mc1972 are the LAT/LON values in decimal degrees, ie. they LOOK like normal LAT/LON values in WGS84 (ie. 37.285543, -100.340014) ? Or do they look like something different? – DPSSpatial Jun 15 '15 at 18:14

Google Earth uses WGS84 as its reference standard. The latest version was created in, you guessed it, 1984. So, we know that your original points utilize a different reference system. You need to find out what that is in order to apply a transformation to your points if you would like to view them accurately in Google Earth.

EDIT: As others have mentioned - NAD27 is a good bet, especially if your data is located in North America.

| improve this answer | |
  • WGS 84 was revised as recently as 2004. – Drew Smith Jun 15 '15 at 18:26
  • 3
    @DrewSmith I think the point was that, the latest version having been created in 1984, it certainly didn't exist in 1969. – user43791 Jun 15 '15 at 18:55

Depending on how the coordinates were sourced (say, off a 1:25k topographical map), 100m error is quite likely. Getting accurate geographical coordinates in the 1960s was a lot more complex operation than it is now. At that time in the UK there is a good chance your coordinates are unprojected UK National Grid coordinates, most topographic mapping at this time used this coordinate reference system. This was called OSGB36 and has EPSG:4277.

So if you convert them to WGS84 they would be 57 08.94N, 2 05.78W.

Which puts it here?

enter image description here

| improve this answer | |
  • 1
    Yes that is the correct place, or certainly within a few m – mc1972 Jun 18 '15 at 8:10
  • It sounds like my answer was the correct one, would you mind marking it correct :-) – TommyMac Dec 10 '15 at 0:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.