/etc/xdg/kstars.knsrc is in kstars-data 4:15.12.3-0ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | [KNewStuff3]
ProvidersUrl=http://edu.kde.org/kstars/downloads/providers.xml
TargetDir=kstars
Uncompress=true
|