Adding coordinate system definitions

You can add support for new projected coordinate systems to Analyst's Notebook Connector for Esri by adding their definitions to the CoordinateSystemWkts file.

When you add a definition of a new coordinate system, you make it possible to visualize chart items that contain geospatial data on new maps in Esri. However, the geospatial data itself must always be in one of the supported coordinate formats.

To add a coordinate system definition:

Create or open the CoordinateSystemWkts file in your roaming application data location.
Search for the projected coordinate system definition in the Esri documentation.
Add the identifier of the coordinate system to the end of the file, followed by a semicolon (;) and its definition.
For example:
```
3388;PROJCS["Pulkovo_1942_Caspian_Sea_Mercator",
GEOGCS["GCS_Pulkovo_1942",DATUM["D_Pulkovo_1942",SPHEROID["Krasovsky_1940",6378245.0,298.3]],
PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],
PROJECTION["Mercator"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],
PARAMETER["Central_Meridian",51.0],PARAMETER["Standard_Parallel_1",42.0],UNIT["Meter",1.0]]
```
Important: Make sure that the definition in the file does not contain spaces or line breaks, and that you specify one of the supported map projections. Esri uses the coordinate system identifier to determine whether to offer a map for selection. If the definition is faulty, users see the map, but are not able to send chart items to it.
If the SPHEROID value is not WGS84, add the datum transformation parameters in a TOWGS84 string. You can find these parameters in the EPSG Registry, and also in the Esri documentation.
1. Search for the transformation from your system to WGS 1984.
  For example, Pulkovo_1942_To_WGS_1984_10.
2. Create a transform string and paste it into the relevant DATUM definition in the CoordinateSystemWkts file.
  For example:
```
TOWGS84[dx,dy,dz,rx,ry,rz,ds]
```
  Where:
  - dx is the x-axis translation (meters)
  - dy is the y-axis translation (meters)
  - dz is the z-axis translation (meters)
  - rx is the x-axis rotation (arc-seconds)
  - ry is the y-axis rotation (arc-seconds)
  - rz is the z-axis rotation (arc-seconds)
  - ds is the scale difference (parts per million)
  The method of transformation in the documentation is described as coordinate frame rotation transformation or position vector transformation.
  
  If the method of transformation is defined as a position vector, then the polarity of the rotation values rx, ry, and rz must be reversed. For example:
```
TOWGS84[43.822,-108.84,-119.58,-1.455,0.761,-0.737,0.549]
```

Make the entry in CoordinateSystemsWkts look similar to this example:

3388;PROJCS["Pulkovo_1942_Caspian_Sea_Mercator",
GEOGCS["GCS_Pulkovo_1942",DATUM["D_Pulkovo_1942",SPHEROID["Krasovsky_1940",6378245.0,298.3],
TOWGS84[43.822,-108.84,-119.58,-1.455,0.761,0.737,0.549]],
PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],
PROJECTION["Mercator"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],
PARAMETER["Central_Meridian",51.0],PARAMETER["Standard_Parallel_1",42.0],UNIT["Meter",1.0]]

Note: Again, make sure that the definition in the file does not contain spaces or line breaks.

Save and close CoordinateSytemsWkts.
Open Analyst's Notebook Connector for Esri. If your server contains base maps or dynamic maps that are based on the newly defined coordinate system, they are now contained in the relevant list of maps.
To check that the new coordinate system is working correctly, use control points whose locations are known:
- Add a chart item with latitude and longitude values for a control point and send it to the map that uses the new coordinate system. Check that the point is displayed at the correct place on the map.
- Query a feature layer that uses the new coordinate system for features whose latitude and longitude values are known. Send these features to a chart and ensure that the latitude and longitude values are correct.