I wrote an iOS app that calculates the Planetary Hours for the current day and night based on a device's (iPhone or iPad) GPS location, and then stores them as events in Calendar:

This is how inter-planetary/inter-dimensional entities keep time. More on that, plus how planetary hours are calculated, coming up; but, in the meantime, catch up on the subject by reading past posts on the relationship between planetary hours and astrology and demonic activity.