Shengong (神宫)

Shengong 1° east of μ_1,2 Sco (WGSN in Stellarium).

Shengong (神宫, Divine Palace) is a subsidiary asterism attached to the lodge Wěi (尾), located to the left of its determinative star and consisting of only a single star.

Concordance, Etymology, History

Chinese "Wei" (Tail)-constellation with a slightly emphasized Milky Way, simulated with Stellarium 2025. The two amorphous regions show that there are many faint stars embedded in bright clouds of the Milky Way. It suggests that ancient astronomers considered these asterisms (or "stars") as "patchy" and not as accurate dots. (Susanne M Hoffmann)

Shengong represents the intimate chamber shared by the emperor and his consorts; for a detailed discussion of its symbolism and origin, see the entry Wěi (尾).

Identification of stars

Shengong (the “Divine Palace”) first appeared in the early eighth century Kaiyuan zhanjing (Divination Canon of Kaiyuan Reign, KYZJ, compiles between 712–718 CE), and was identified with μ² Scorpii. Because μ¹ and μ² are separated by only 0.1°, it is conceivable that some observers could not distinguish between the two and regarded them as a single star. In that case, Shengong should have been observed as another star.

Another possible cause of misidentification lies in the star maps themselves. Many historical star maps—such as those in Xinyixiangfayao star map—depict the distance between Shengong and μ² as much larger than it actually is. For whatever reason, the observers of Jingyou Star Catalogue (compiled in 1034 CE by Yang Weide) identified Shengong as a different star: the coordinates they obtained with the armillary sphere were about one degree away from μ¹, far exceeding the real separation of 0.1°. In the star map shown below (second row, second column), the black square marks the coordinate observed in 1034.

The position of Shengong would thus correspond either to HIP 83100, which has a visual magnitude of 6.05, or to HIP 83491, which lies slightly farther east but is somewhat brighter (V = 5.9 mag).

Susanne M Hoffmann points out:

Look at the simulation in Stellarium. Both stars in question (HIP 83100 and HIP 83491), as well as HIP 83499 (6.51 mag) and several other faint stars, are embedded in a patch of Milky Way clouds. Against the bright background of the Milky Way, it is rather difficult to distinguish the faint dots.

In an (unpublished) paper some years ago, I proposed (or will propose) regarding Ptolemy’s Almagest that his term “nebulous star” refers to such scenarios. I demonstrated (based on coordinates) that all of his “nebulous stars” are in fact small groups of two or more faint stars embedded in Milky Way clouds. They are not necessarily star clusters in the modern sense but regions in the sky where, under poor observing conditions (such as the humid climate of Alexandria on the Egyptian coast), the human eye perceives only something “nebulous”—a hazy patch. For example, Ptolemy gives three coordinates in Coma Berenices and instructs the globe-maker to “draw an ivy leaf” anchored at these three points. Likewise, he gives one coordinate and says “draw the head of Orion around it,” implying that the “head” was conceived as an extended area rather than a single point.

…I think you can safely choose any one of the stars around 6th magnitude without fear of criticism.

This is an excellent point: for observers of that period, who were not necessarily pursuing strict precision, Shengong might have referred to any of the faint stars in that region—or even to the entire patch itself.

However, Boshun Yang and his Chinese colleague have identified another pattern: within this area, the coordinates of stars recorded in the Jingyou Star Catalogue show a common systematic error among the observed objects (indicated by the red arrow in the star map of the second row, second column). Based on this systematic offset, HIP 83100 appears to be the more probable target of measurement.

Therefore, taking all clues into account, we finally identify HIP 83100 as the Shengong during the Jingyou period, although HIP 83491 may have been regarded as Shengong in other periods.

Star Names or Orders(Traditional/Qing)	Yi Shitong Based on catalogue in 18th century	Pan Nai based on Xinyixiangfayao Star Map	Pan Nai based on catalogues in Yuan dynasty	Boshun Yang Song Jingyou(1034)
Shengong	NGC 6231	mu2 Sco	mu2 Sco	HIP 83100

Maps (Gallery)

Wei and Shengong

historical map	modern identification	same in Stellarium
Wei and Shengong in Xinyixiangfayao Star Map (Song Dynasty)	Wei and Shengong observed in 1052 reconstructed by Pan Nai (2009)	Wei in Stellarium 25.3
	Wei and Shengong observed in 1034 Reconstructed by Yang Boshun	Wei and Shengong observed in 1034 demonstrated in Stellarium
Wei and Shengong in Jesuits Star Map in 17th Century	Wei and Shengong Reconstructed by Yi Shitong(1981)	Wei and Shengong observed in Qing Dynasty demonstrated in Stellarium 25.3: here the name "Shengong is shifted to the open star cluster NGC 6231.

Star Name Discussion (IAU)

In 2025, the name of the historical constellation "Shengong" was suggested to be used for one of the stars in this constellation. As mu² Sco was named as Pipirima already, it is proper to apply Shengong to HIP 83100, a 6.05 mag star in Scorpius.

Decision: ...

References

References (Chinese)