Installing the IAU authority
The IAU authority is an official extension. Download the extension here - http://sourceforge.net/projects/geoserver/files/GeoServer/2025.1/extensions/geoserver-2025.1-iau-plugin.zip
- Download the extension for your version of GeoServer. - Warning - Make sure to match the version of the extension to the version of GeoServer. 
- Extract the archive and copy the contents into the GeoServer - WEB-INF/libdirectory.
- Restart GeoServer. 
Verify Installation
To verify that the extension was installed successfully:
- On the left menu, get into Demos and then SRS List 
- Go into the table filter text field, and type IAU, then press enter 
- A number of IAU codes should appear in the table 
