So basically the #DOW# tag is day of week 0-6, and the range you're trying to cover is 218 degrees. So the first part adds 216/7 [~31] degrees every day. the second half (after the +) adds 24 hour rotation (0-359 degrees) / by 35/3 ( 360 / (35/3) = ~ 216/7 ). The -108 sets the beginning to -108 degrees. Basically it adds ~31 degrees every day after the first and 1.28 degrees every hour. In theory this should appear fluid in motion.