I think you explained what I was asking
There is data coming from the Cayman Islands, a timeshift is applied to bring this data in line with your tank lighting period, desired sunrise / sunset. So it uses real data, at a different time to suit your time zone.
Yes, correct. But the shift is pretty minor or zero (in winter time). The sunrise on cayman islands starts at 6:00 AM which is 13:00 (12:00 in winter) here in germany, that is nearly perfect for me. I always had late sunrise/sunset times at my tank, because i want to enjoy it, when i come back home from work. so my lighting period goes from 1:00 pm to 1:00 am.