Here's what I'd do...

Have the NEIC catalog as it's own separate file.

Have a small program to read that file and generate your sun/moon data for each quake and save it in it's own separate file. There should be a 1-to-1 correspondence for each line of these files.

Then, your main program accesses these files as needed.

Should you need to update the NEIC file, then all you do is run the utility program to regenerate the sun/moon file.

Just a thought.

Brian