The Jungseong-gi (中星紀, List of Centered Stars) recorded on the Cheonsang Yeolcha Bunyajido (Chart of the Constellations and the Regions They Govern, 天象列次分野之圖) refers to the celestial coordinates of stars that culminate at the meridian during evening and morning twilight at the twenty-four solar terms. By comparing these stellar positions with modern astronomical calculations and results obtained using the Shoushi-li method, this study examined the accuracy of timekeeping at night during the late Goryeo and early Joseon periods. The analysis reveals systematic deviations from the theoretical positions. Yu Bang-taek’s calculations were based on sunrise times uncorrected for latitude and therefore effectively referenced Beijing rather than the central Korean Peninsula. Among the forty-eight hun-xiao Centered Stars, six cases have lower bounds of discrepancies of at least 1.5 degrees when evaluated at the level of the twenty-eight lunar mansions, and in two of these cases the lower bounds are close to or exceed 4 degrees. These values should not be understood as literal errors in angular computation but as reflecting limitations inherent in nighttime time determination. They indicate that the practical accuracy of nighttime timekeeping was on the order of ±1 to ±2 gak (刻; approximately ±15 to ±30 minutes in modern time). This study also proposes that the original astronomical chart that served as the basis for the Cheonsang Yeolcha Bunya Jido was most likely produced during the Goryeo period, rather than in the traditionally accepted Goguryeo period.