/usr/share/kstars/neptune.L4.vsop 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 | -0.00000113998 0.000000 0.000000
0.00000000605 3.18211885677 76.2660712756
|