Kulou

File:Kulou on the Suzhou Star Chart.jpg

Kulou on the Suzhou Star Chart

"Kulou" means arsenal and storied building, is a constellation in the area of modern Cen/Lup created by ancient Chinese astrologers, dating back to the 2nd century BCE. It is classified as one of the "external" constellations (外官) of the Shi School (石氏), as it belongs to the Shi School's constellation system during the Han Dynasty, and it is outside of the 28 lunar mansions.

Etymology and History

Kulou includes various sub-constellations such as "Ku" (库, arsenal, 6 bright stars), "Lou" (楼, storehouse, 4 fainter stars), "Wu-Zhu" (五柱, literally 'five pillars,' but interpreted as military chariots in astrology, 3stars for each "pillar"), and "Heng" (衡, possibly the graduated arm of a steelyard weighing apparatus or the crossbar at the front of a chariot, 4 stars), totaling 29 stars.

In the Western Han period, the names for Kulou were diverse, including "Tinaku (天库, celestial arsenal)," "Tian Kulou (天库楼, celestial arsenal and storied building)," and "Tian Lou (天楼, celestial storied building)" as referred to by Jiaoyan Shou (1 century BCE), all of which are alternative names for "Kulou."

Identification of stars

In Sima Qian's "Book of Heavenly Officials" (天官书), an early reference to Kulou is made, though the exact number of stars is not specified. The text provides a vague description: "南众星曰天库楼，库有五车" ("The southern group of stars is called Tian Kulou, with five chariots in the arsenal"), but it mentions "five chariots" instead of "five pillars," and makes no mention of Heng. Similarly, the "Huangdi Zhan" (黄帝占) follows the same naming convention, referring to Kulou as the "Outer Ku" (外库) and describing the five pillars as "Wu Che" (five chariots). This suggests that the early Ku Lou constellation's five pillars/chariots were likely all contained within the arsenal.

After the constellations were redefined during the Taichu (104 BCE -102 BCE) period of the Western Han, the Kulou constellation was expanded to include "Heng," and one of the pillars was moved to the north of Kulou, as later Suzhou Star Map depict. Jiaoyan Shou's mention that "天楼星上近柱，王者楼殿有飞 (If the stars of Tian Lou go upwards to approach the pillar, indicating that the ruler's palace will fly (to other places))" seems to suggest that one of the pillars had indeed moved above Kulou.

The primary star of this constellation is almost always Iota Centauri after the Han Dynasty.

Star Names or Orders(Traditional/Qing)	Order(Qing Dynasty)	Ho PENG YOKE	Yi Shitong Based on catalogue in 18th century (Qing Dynasty)	Pan Nai based on Xinyixiangfayao Star Map	SUN X. & J. Kistemaker Han Dynasty	Boshun Yang before Tang dynasty	Boshun Yang Song Huangyou(1052)
Ku	1st/determinative	zeta Cen	zeta Cen	iota Cen	iota Cen	iota Cen	iota Cen
	2nd	eta Cen	eta Cen	upsilon1 Cen	epsilon Cen	zeta Cen	zeta Cen
	3rd	theta Cen	theta Cen	eta Cen	alpha Lup	alpha Lup	alpha Lup
	4th	g Cen	g Cen	theta Cen	eta Cen	eta Cen	eta Cen
	5th	d Cen	d Cen	g Cen	theta Cen	theta Cen	theta Cen
	6th	e Cen	f Cen	HIP 64408	gamma Cen	HIP 64348	HIP 64408
Lou	7th	gamma Cen	gamma Cen	HIP 63972	alpha Cru	gamma Cen	n Cen
	8th	tau Cen	tau Cen	HIP 64332A	Beta Cru	tau Cen	HIP 63066
	9th	E Cen	HIP 60517	HIP 64557	gamma Cru	G Cen	HIP 64468
	10th	sigma Cen	sigma Cen	HIP 64348	delta Cru	sigma Cen	l Cen
Heng	1st/determinative	nu Cen	nu Cen	nu Cen	nu Cen	nu Cen	nu Cen
	2nd	mu Cen	mu Cen	mu Cen	mu Cen	mu Cen	mu Cen
	3rd	phi Cen	phi Cen	phi Cen	phi Cen	phi Cen	phi Cen
	4th	chi Cen	chi Cen	chi Cen	chi Cen	chi Cen	chi Cen
Zhu	1st	upsilon2 Cen	upsilon2 Cen	zeta Cen	upsilon2 Cen	upsilon2 Cen	upsilon2 Cen
	2nd	upsilon1 Cen	upsilon1 Cen	HIP 67663	upsilon1 Cen	upsilon1 Cen	upsilon1 Cen
				upsilon2 Cen	zeta Cen	HIP 68079	HIP 68079
Zhu	3rd	iota Lup	iota Lup	iota Lup	rho Lup	iota Lup	iota Lup
	4th	tau1 Lup	tau1 Lup	tau1 Lup	sigma Luo	tau1 Lup	tau1 Lup
				HIP 70104	HIP 70931	HIP 70104	HIP 70104
Zhu	5th	a Cen	a Cen	a Cen	iota Lup	a Cen	a Cen
	6th	psi Cen	psi Cen	psi Cen	tau1 Lup	HIP 69598	HIP 69598
				HIP 68493	HIP 70104	HIP 70054	HIP 70054
Zhu	7th	h Cen	h Cen	h Cen	a Cen	k Cen	k Cen
	8th	k Cen	k Cen	k Cen	psi Cen	i Cen	i Cen
	9th	i Cen	i Cen	i Cen	HIP 70987	g Cen	g Cen
Zhu	10th	HIP 64003	?	d Cen	k Cen	d Cen	d Cen
	11th	iota Cen	iota Cen	HIP 65535	i Cen	HIP 65535	HIP 65535
				HIP 65593	g Cen	HIP 65593	HIP 65593

Maps

historical map	modern identification (Yang 2023)	same in Stellarium 24.4
Kulou on the Cheonsang Yeolcha Bunyajido Star Chart
Kulou on the Geziyuejintu(Tang Dynasty)	Kulou between Han and Tang Dynasty as drawn on the Cheonsang Yeocha Bunyajido and Geziyuejintu, identified by Boshun Yang (2023).	Kulou between Han and Tang Dynasty as drawn on the Cheonsang Yeocha Bunyajido and Geziyuejintu, mapped in Stellarium 2024 by Boshun Yang (2023)
Kulou on the Suzhou Star Map	Kulou as drawn on the Suzhou map in Song Dynasty (China), identified by Boshun Yang (2023).	Kulou as drawn on the famous Suzhou Star Chart from Song Dynasty China, mapped in Stellarium 2024 by Boshun Yang (2023).

• Kulou
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  Kulou on the Cheonsang Yeolcha Bunyajido Star Chart

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  Kulou on the Geziyuejintu(Tang Dynasty)

• Kulou on the Suzhou Star Chart.jpg

  Kulou on the Suzhou Star Chart

Star Name Discussion (IAU)

In 2023, the name of the historical constellation was suggested to be used for one of the stars in this constellation. The determinative star of Kulou is Iota Centauri, ι Cen (2.73 mag, triple A-type star SIMBAD) and would therefore be the first choice.

Furthermore, there are some subsidiary this constellation, such as Heng. "Heng" should become the star name for its determinative star, Mu Cen (3.43 mag SIMBAD, Be-star, slightly variable, between 2.92 - 3.47 V).

Decision: ...

References

• All Chinese References