Running 64 bit Mint 18. Install worked just fine. The instruction to run xflux was fine. Just one point, if you live in the western hemisphere don''t forget to put a - in front of your longitude. For example, -95.55 instead of 95.55. When I put in 95.55 it told me it was night and the screen dimmed down. At least I knew it worked. I imagine the same holds true for those in the southern hemisphere.
Look forward to playing with this tool.