AnnotateDaylight        Annotate ggplot with a band indicating solar
                        events
AnnotateLunarphase      Annotate ggplot with lunar phases
CoordHourglass          Hourglass coordinates for a ggplot
GeomHourglass           Add an 'hourglass' layer to a ggplot
StatHourglass           A ggplot2 'stat' function to wrangle data for
                        'geom_hourglass'.
annotate_periodstates   Annotate a period in an hourglass plot
bats                    Observations from a bat detector
get_hour                Functions to split datetime into date and time
                        of day
lunar_phase_polygon     Get the shape of the illuminated part of the
                        moon
uses_dst                Test if datetime object potentially uses
                        daylight saving time
