Useful tools and tables!
Click to download a spreadsheet with a VBA module that batch-converts Lat-Long from Degrees Minutes Seconds to Decimal degrees and vice-versa. Make sure you enable macros in order to run on your machine
Click to download Steven Dutch's UTM converter spreadsheet. This is not my work, the author permits distribution with attribution
| Ellipsoid name: | Semi Major axis (a): | Semi Minor axis (b): | Flattening (f): | Inverse flattening (1/f): | Comments: |
|---|---|---|---|---|---|
| WGS84 | 6378137.0 | 6356752.314245 | 0.00335281066474748 | 298.257223563 | WGS84 is both an ellipsoid and an almost-complete CRS on its own (the only thing it doesn't specify is a projection so most proj4 systems will default to Equirectangular). The ellipsoid is a very slightly amended GR80 ellipsoid. |
| GR 80 | 6378137.0 | 6356752.3 | 0.003352811 | 298.257 | Is the basis for the WGS84 ellipsoid. The difference is imperceptible for topographic applications |
| WGS 72 | 637813.0 | 6356750.5 | 0.003352783 | 298.260 | Deprecated. Superseded by WGS84 |
| Australian 1965 | 6378160 | 6356774.7 | 0.003352895 | 298.250 | Don't know |
| Krassovsky 1940 | 6378245.0 | 6356863.0 | 0.003352333 | 298.300 | Used in Pulkovo 1942 and all its derived PCSs such as Stereo 70. Very popular in ex-USSR and still highly relevant |
| North American 1927 | 6378206.4 | 6356583.8 | 0.003390075 | 294.979 | Superseded by NAD83 for State Planar |
| Hayford 1909 | 6378388.0 | 6356911.9 | 0.003367011 | 296.999 | Deprecated but highly relevant. Was the default choice in Europe before the adoption of ETRS89 (datum based on the WGS84 ellipsoid). It was used in ED50 and therefore all its derived PCSs. It is still used in Monte Mario |
| International 1924 | 6378388.0 | 6356911.9 | 0.003367011 | 296.999 | This is the Hayford 1909. It was renamed when the IUGG officially adopted it in 1924 |
| Clarke 1880 | 6378249.1 | 6356514.9 | 0.003407550 | 293.466 | Don't know |
| Clarke 1886 | 6378206.4 | 6356583.8 | 0.003390075 | 294.979 | Don't know |
| Airy 1830 | 6377563.4 | 6356256.9 | 0.003341 | 299.325 | Used in the OSGB36 datum and therefore the British National Grid |
| Bessel 1841 | 6377397.2 | 6356079.0 | 0.003343 | 299.153 | Don't know |
| Everest 1830 | 6377276.3 | 6356075.4 | 0.003324 | 300.802 | Don't know |
The following locations were used as prime meridians in their own right before the adoption of Grenwich. For almost all of them I could find logged offsets on the proj.4 library files so I used those (format: Degrees, Minutes, Seconds). Conversion to DD is my own work, but as will be immediately obvious the conversion is to more decimal points than the DMS dataset. Again, I shall bear no responsibility for erroneous calculations.
| Name | Countries of use | Offset from ITRS in DD | Offset from ITRS in DMS |
|---|---|---|---|
| Greenwich | UK, Global | 0 | 0 ° |
| Lisbon | Portugal, Old European Maps | -9.1319061 | 9° 7' 54.862" W |
| Paris | France | 2.3372292 | 2° 20' 14.025" E |
| Bogota | South America | -74.0809167 | 74° 4' 51.3" W |
| Madrid | Spain | -3.6879111 | 3° 41' 16.48" W |
| Rome | Italy | 12.4523333 | 12° 27' 8.4" E |
| Bern | Austria | 7.4395833 | 7° 26' 22.5" E |
| Jakarta | Indonesia | 106.8077194 | 106° 48' 22.79" E |
| Ferro | Limit of the Old World | -17.6666667 | 17° 40' 0" W |
| Brussels | Belgium | 4.367975 | 4° 22' 4.71" E |
| Stockholm | Sweden | 18.0582778 | 18° 3' 29.8" E |
| Athens | Greece | 23.7163375 | 23° 42' 58.815" E |
| Oslo | Norway | 10.7229167 | 10° 43' 22.5" E |
| Pulkovo | Russia | 30.266667 | 30° 19' 36" E |