Load Easting/Northing table into ArcGIS and convert coordinates

So I got an email from one of our GIS users:

Hi Karl, I need to convert some large files with XY Easting/Northing coordinates to latitude and longitude. Do you have any idea how to do this in STATA or GIS?

I assume the input data is in some tabular format that ArcGIS can read – MS Excel, Access, CSV, etc, and the input coordinates are British National Grid. So this is how it works:

  1. Start ArcMap
  2. Load the input data:
    1. Fo to File > Add Data. Add your input table. This can be an Excel worksheet, CSV file, dBase file, MAS Acess table, Geodatabase table, ….
    2. Open the table and check that all data is loaded correctly
  3. Make it spatial:
    1. Right-click in the data frame and set the coordinate system to whatever your Easting/Northing is in, e.g. British National Grid
    2. File > Add Data > Add XY data
    3. Specify the input data table, X and Y field, and input coordinate system
    4. you now see a new map layer named <inputtable>$Events
    5. right-click  the layer name , Export > Export data. This creates a Shapefile, call it e.g. MySurvey_BNG.shp. When asked if you want to add the new file to the project, say Yes.
  4. Convert to Lat/Lon
    1. Go to ArcToolbox > Data Management > Projections and Transformations > Features > Project.
    2. Select Input layer MySurvey_BNG. The Input Coordinate System will be set automatically. Specify output location and name, e.g. MySurvey_DD.shp. Click the icon next to Output Coordinate System and select Geographic > World > WGS1984, OK. From the transformation drop-down lists select  ‘OSGB_1936_to_WGS_1984_Petroleum’ .
  5. Add fields with Lat/Lon coordinates
    1. Go to ArcToolbox > Data Management > Features > Add XY Coordinates.
    2. Specify the projected layer (MySurvey_DD). OK
    3. When the tool finishes open the attribute table for the projected Layer (MySurvey_DD). It now contains fields Point_X and Point_Y in Decimal Degrees on WGS1984.
  6. Export to other software (MS Excel, SPSS, etc.): In the table click the top left button > Export. Export to dBase or Text.

Note: If you work with Geodatabase instead of Shapefiles the X and Y fields will be added automatically, you don’t need to calculate them.


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