Journal of Astronomy in Culture

Koh Ker is an ancient Khmer city built in Cambodia in the 10^th century CE. While most Khmer temple complexes were built with cardinal or near cardinal direction orientations, Koh Ker has a section that is instead oriented to sunrise on the day of zenith passage.  The Koh Ker complex of Prasat Thom is linear and oriented to 14 degrees north of east.  The Prang Pyramid at Prasat Thom’s western end overlooks the entire alignment to a flat horizon where the zenith passage sun rises.  Along that same 14-degree axis are zenith passage tubes in roofs and linga statues acting as gnomons to capture the exact moment of zenith passage at noon.  This report presents the results of a project to photo document the zenith passage sunrise alignment from the top of the Prang Pyramid.  It ends by providing evidence that Koh Ker’s alignments are not an enigma by citing zenith passage related architectural features in Java, Sri Lanka, and the nearby Khmer city of Angkor.