One of the most basic kernel data files needed is in the LSK kernel directory LKS Kernel file naif0012.tls.

This file is a LSK (“leap seconds”) Kernel. It is a “text kernel file” meaning its data can be viewed/edited in a text editor.

The data is very basic; it is just a list of all the leapseconds since January 1972. Many calculations will err if there’s not a LSK kernel file (like this one) loaded. naif0012.tls is the most recent version, so it’ll do - until another leap second is declared.

For most purposes, naif0012.tls will suffice.