Archaeoastronomical Analysis of Sri Suphan Temple

Archaeoastronomical studies in the ancient Lanna Kingdom, centered in Chiang Mai Province in northern Thailand, have revealed the influence of Vastu Shastra principles, an ancient Indian treatise of architecture, on the alignments of cities and temples with auspicious stars. This paper investigates the orientation of Sri Suphan Temple, a royal Buddhist temple built in King Mueng Kaew’s reign in 1503 during the Vaisakha lunar month, that has a similar orientation to the renowned Phra That Doi Suthep Temple, which was previously studied to be aligned with a star marking Vaisakha Nakshatra around 1537. We surveyed the site using a theodolite, a GPS device, and Stellarium astronomy software to yield the orientation of the temple with an azimuth angle of 58.94 ± 0.08°. Using precession-corrected Stellarium computation to trace stars’ azimuths back in time and reveal their annual path behavior, we find Alphecca, with an azimuth of 59.45 degrees, rising on the eastern horizon during Vaisakha month as indicated in the inscription, to be the most probable star of alignment. Alphecca is a bright star in the Corona Borealis Constellation reported to be the same star used in the Doi Suthep Temple, which suggests that the Sri Suphan Temple may have been a prototype for aligning later Buddhist temples.