Gold leaf was used in drawing Japan's oldest existing astronomical charts covering the ceiling of an ancient tomb in the village of Asuka, Nara Prefecture, the Cultural Affairs Agency said.
The latest Kitora findings came Thursday as researchers filmed the stone chamber of the tomb for the fourth time, inserting a digital camera attached to the tip of a 3.5-meter arm through a grave robbers' tunnel.
The constellations were drawn with gold leaf connected by red lines made of cinnabar, a mercuric sulfide pigment, agency officials said.
The Kitora tomb dates from the late seventh century to early eighth century, with its mound measuring about 14 meters in diameter and 2.6 meters high. Wall paintings were discovered there in 1983.
Researchers knew of the astronomical charts from earlier filmings, but this is the first time that the use of gold leaf has been confirmed.
The latest filming was conducted to gather information on the scope of the tomb and the condition of a tunnel used by grave rubbers ahead of full-scale restoration work set to begin next year on the tomb's mural paintings.
The tomb is situated about 1 km south of the Takamatsuzuka mound, which carries plastered and painted walls.