IK kernels describe spacecraft instrument configuration details.

These files contain data about instruments such as cameras and their field of view. The data is used to determine what is currently in a Spacecraft’s camera’s field of view.

These files are in text format and are viewable in any text editor.

More information can be found by downloading the IK Kernel tutorial:
https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/Tutorials/pdf/individual_docs/25_ik.pdf