Tiancang (天倉)
Tiancang
Authors: Lyu Haocheng, Susanne M Hoffmann
Tiān Cāng (天倉, Square Celestial Granary) is a Chinese asterism belonging to the Lou (婁) (Bond) lunar mansion. Among the Three Schools of ancient Chinese astronomy, it is classified as an external constellation of the Shi School (石氏). The asterism consists of 6 stars located to the south of Lou, within the modern constellation Cetus.
| Asterism Info | |
| Native | 天倉 |
|---|---|
| Romanisation | Tiān Cāng |
| IPA | /tʰjɛn˥.t͡sʰɑŋ˥/ |
| Translation | Square Celestial Granary |
| Position (2000) | |
| Right ascension | 11.04770833 to 30.0035 |
| Declination | -21.08013889 to -8.184472222 |
| Area | 0 sq. deg. |
| Stars | |
| Bright stars | 6 |
| Bayer/Flamsteed stars | 6 |
| Stars brighter than 3.00m | 0 |
| Brightest star | η Cet (3.45m) |
| Taxonomy | |
| category of asterism | constellation |
| IAU- constellations | Cet |
Concordance, Etymology, History
The name Tiān Cāng combines tiān (天, celestial) with cāng (倉), which denotes a square granary or storehouse in classical Chinese. The Shuowen Jiezi (説文解字) glosses cāng (倉) as "a place where grain is stored" (穀藏也), while later commentaries distinguish between cāng (倉, square, roofed granary) and qūn (囷, circular granary). The asterism thus represents the square granary of heaven, complementing the circular granary Tianqun (天囷) to its east.
The origin of Tiancang is directly linked to the pasturage and sacrificial symbolism of the Lou (婁) mansion. The Shi Shi Zan (石氏讚, Shi's Eulogy) explicitly states:
Lou (婁) governs the pastures and the provision of sacrificial offerings; therefore Tiancang was established to nourish them. (婁主苑牧，給享祀，故置天倉以養之).
The Shiji·Tianguan Shu (史記·天官書, Treatise on the Celestial Offices) also associates the region south of the Wei (胃) mansion with a celestial storage complex:
Wei (胃) is the celestial granary. The many stars to its south are called Kuài Jī (廥積, stores of hay and grain).
Tiancang, together with Tianqun (天囷) and the related granary asterisms, was differentiated from this general southern storage region.
In astrological texts, Tiancang was understood as the celestial agricultural office (天司農), governing the storage of grain in state granaries. The Huangdi Zhan (黄帝占) records that when the stars within Tiancang are numerous, grain is gathered and the stores are full; when they are few, the granaries are empty and grain is dispersed. The Shi Shi adds that when the "door" of Tiān Cāng is open, the year will be one of great harvest; when closed, the grain will not ripen and the people will suffer famine. Xi Meng (郗萌) notes that if the stars of Tiancang are incomplete, the roads will be impassable.
Identification of stars
Before the late Ming dynasty, the identification of the six stars of Tiancang was relatively consistent. The determinative star was the northwestern star, identified as θ Ceti, though some sources identify it as η Ceti.
| Star Names or Orders(Qing) | Han Dynasty (SUN X. & J. Kistemaker[1]) | 3rd to 6th Century (Boshun Yang[2]) | Song Dynaty (Boshun Yang[2], 1034 CE) | Song Dynasty (Pan Nai[3], 1052 CE) | Song Dynasty (Boshun Yang[2], 1052 CE) | Yuan Dynasty (Pan Nai[4], 14th century) | Qing Dynaty (Yi Shitong[5], 18th Century) | Ho PENG YOKE[6] |
|---|---|---|---|---|---|---|---|---|
| 1st | ι Cet | φ1 Cet | φ1 Cet | φ1 Cet | φ1 Cet | φ1 Cet | ι Cet | ι Cet |
| 2nd | η Cet | η Cet | η Cet | η Cet | η Cet | η Cet | η Cet | η Cet |
| 3rd | θ Cet | θ Cet (determinative) | θ Cet (determinative) | θ Cet (determinative) | θ Cet (determinative) | θ Cet | θ Cet | θ Cet |
| 4th | ζ Cet | ζ Cet | ζ Cet | ζ Cet | ζ Cet | ζ Cet | ζ Cet | ζ Cet |
| 5th | τ Cet | τ Cet | τ Cet | 47 Cet | τ Cet | τ Cet | τ Cet | τ Cet |
| 6th | υ Cet | υ Cet | υ Cet | τ Cet | υ Cet | υ Cet | 57 Cet | 57 Cet |
Maps (Gallery)
| historical map | modern identification | same in Stellarium |
|---|---|---|
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_reconstructed_by_Pan_Nai_(2009).png) _reconstructed_by_Boshun_Yang_(2023).png) | |
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_in_Stellarium.png) |
IAU Working Group on Star Names
In 2026, the name of the historical constellation "Tiancang" was suggested to be used for θ Ceti in this constellation, as it is the historical determinative star.
Decision: ...
References
References (Chinese) [[Category: ]]
- ↑ Sun Xiaochun. & Kistemaker J. The Chinese sky during the Han. Leiden: Brill. 1997, Pp241-6.
- ↑ 2.0 2.1 2.2 B.-S. Yang杨伯顺, Zhongguo Chuantong Hengxing Guance Jingdu ji Xingguan Yanbian Yanjiu 中国传统恒星观测精度及星官演变研究 (A Research on the Accuracy of Chinese Traditional Star Observation and the Evolution of Constellations), PhD thesis, (Hefei: University of Science and Technology of China, 2023), Pp297-304.
- ↑ Pan Nai潘鼐. Zhongguo Hengxing Guance shi中国恒星观测史[M]. Shanghai: Xuelin Pree. 1989, Pp220-226.
- ↑ Pan Nai潘鼐. Zhongguo Hengxing Guance shi中国恒星观测史[M]. Shanghai: Xuelin Pree. 2009. p435-443.
- ↑ Yi Shitong伊世同. Zhongxi Duizhao Hengxing Tubiao中西对照恒星图表1950. Beijing: Science Press.1981.
- ↑ P.-Y. Ho, “Ancient And Mediaeval Observations of Comets and Novae in Chinese Sources,” Vistas in Astronomy, 5(1962), 127-225.
