Nachi-Katsuura Observatory is an astronomical observatory in Nachikatsuura, Wakayama, Japan. Facing the Pacific Ocean, it lies within the Yoshino-Kumano National Park.[1] It is 0.83368 Earth radi from the rotational axis of the Earth, and +0.55040 Earth radii above the equatorial plane.[2] The IAU observatory code for Nachi-Katsuura is 905.[3]