Sundial on Oort building roof
The Leiden Observatory has erected part of very large scale sundial on top of the Oort building roof. This section consists of a disk of 2.5m diameter with a hole of 0.8m diameter. When the sun shines the disk throws a shadow with a centralized bright spot on the parking lot in front of the Oort building. This bright spot can be used to mark the position of the Sun at a specific time and date. When this spot is marked for a period of one full year the scales of the Sundial will start to emerge on the parking lot.
A sketch of the final result is shown here:
Red and blue lines denote the different months of the year, black lines denote the different hours of the day.