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{{DISPLAYTITLE: Waiping (外屏)}} 

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[[File:Waiping in Stellarium.png|alt=Waiping in Stellarium|thumb|400x400px|Waiping in Stellarium]]
Wài Píng (外屏, Outer Fence) is a traditional Chinese asterism belonging to the [[Kui]] mansion. Among the Three Schools of ancient Chinese astronomy, it is classified as a Gan School asterism (甘氏星). The asterism consists of seven stars located south of [[Kui]]. In modern constellation boundaries, Waiping lies within [[Pisces]].

== Concordance, Etymology, History ==
The name "Wài Píng" literally means "Outer Fence" or "Outer Screen" — a barrier on the outside. The seven stars of Waiping are positioned south of [[Kui]] to shield and block foul odours. The Gan Shi Zan (甘氏讚 / Gan's Eulogy) states:<blockquote>"The fence encloses and conceals; the pigsty remains unseen."</blockquote>The establishment of Waiping is closely connected with Tianhun (天溷, Celestial Pigsty) to its south. The character hùn (溷) carries a dual meaning, referring to both a pigsty and a latrine — a building complex where the latrine was attached to the pigsty. Tianhun lies south of Waiping, and the function of Waiping is precisely to block the foul odours emanating from Tianhun. The Tang dynasty poet Li Bo (李播), in his ''Tianwen Daxiang Fu'' (天文大象賦 / Rhapsody on the Great Images of the Celestial Sphere), writes:<blockquote>"The circular granary (Tianqun, 天囷) and the square granary (Tiancang, 天倉) are established for storing and gathering; the pigsty (Tianhun, 天溷) and the fence are erected in overlapping layers." (立囷倉之儲聚，樹溷屏之重復。)</blockquote>Here, "pigsty" and "fence" refer to Tianhun and Waiping respectively, while "overlapping layers" describes the layering of screens — barrier upon barrier — erected to block and conceal foul odours.

=== Naming and Etymology ===
The Chinese character píng (屏) can mean a fence, screen wall, or folding screen. As a Gan School asterism, the name "Outer Fence" (外屏, Wàipíng) stands in clear opposition to the Inner Screen (內屏, Nèipíng) of the Shi School. In the Chinese asterism system, there are three "screen"-related asterisms: the Shi School's Inner Screen and [[Ping|Screen (屏, Píng)]], and the Gan School's Outer Fence. The Inner Screen is located inside the main gate (端門, Duānmén) of the Supreme Palace Enclosure (太微垣, Tàiwēi Yuán), serving to shield the Celestial Court so that the Emperor's Seat within cannot be seen directly from outside. Another [[Ping|Screen]] asterism is placed in front of the Toilet asterism (廁, Cè), also for the purpose of shielding. The Outer Fence, though belonging to the Gan School rather than the Shi School, serves a similar function: to shield the Celestial Pigsty (Tianhun) to its south from view.

=== History ===
The use of a píng (屏, screen wall) to enclose a latrine is already attested in pre-Qin texts. The Mozi (墨子), in the chapter "Flags" (Qízhì, 旗幟), records:

"Outside the roadway a screen wall (屏, píng) should be built; thirty paces beyond it a circular enclosure (圜, yuán) is to be constructed, one ''zhang'' in height. This is to serve as the people's latrine (圂, hùn), with walls no less than twelve ''chi'' high."

Here, píng refers to a screen wall used to enclose the latrine, while hùn (圂/溷) was another ancient designation for a toilet. This matches exactly the celestial arrangement of the Outer Fence shielding the Celestial Pigsty.
 
=== Identification of stars ===

The identification of the seven stars of Waiping is well established. The determinative star is the westernmost star, identified as δ Psc.

{| class="wikitable"
|+
!Star Names or Orders(Qing)
! style="color: gray;" |Han Dynasty
(SUN X. & J. Kistemaker<ref>Sun Xiaochun. & Kistemaker J. ''The Chinese sky during the Han''. Leiden: Brill. 1997, Pp241-6.</ref>)
!before Tang dynasty: 3rd to 6th Century
(Boshun Yang<ref name=":1">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). 235-296.</ref>)
!Song Dynaty: Jingyou, 1034
(Boshun Yang<ref name=":1" />)
! style="color: gray;" |Song Dynaty: Huangyou, 1052
(Pan Nai<ref name=":0">Pan Nai潘鼐. ''Zhongguo Hengxing Guance shi''中国恒星观测史[M]. Shanghai: Xuelin Pree. 1989. Fig 55.</ref>, based on ''Xinyixiangfayao'' Star Map)
! style="color: gray;" |Yuan dynasty: 1279-1368
(Pan Nai<ref>Pan Nai潘鼐. ''Zhongguo Hengxing Guance shi''中国恒星观测史[M]. Shanghai: Xuelin Pree. 2009. p435-443.</ref>)
! style="color: gray;" |Qing dynasty: 18th Century
(Yi Shitong<ref>Yi Shitong伊世同. ''Zhongxi Duizhao Hengxing Tubiao''中西对照恒星图表1950. Beijing: Science Press.1981.</ref>)
! style="color: gray;" |Ho PENG YOKE<ref>P.-Y. Ho, “Ancient And Mediaeval Observations of Comets and Novae in Chinese Sources,” ''Vistas in Astronomy'', 5(1962), 127-225.</ref>
|-
| 1st (Determinative)
| style="color: gray;" | δ Psc
| δ Psc
|  δ Psc
| style="color: gray;" | δ Psc
| style="color: gray;" | δ Psc
| style="color: gray;" | δ Psc
| style="color: gray;" | δ Psc
|-
| 2nd
| style="color: gray;" | ε Psc
| ε Psc
| ε Psc
| style="color: gray;" | ε Psc
| style="color: gray;" | ε Psc
| style="color: gray;" | ε Psc
| style="color: gray;" | ε Psc
|-
| 3rd
| style="color: gray;" | ζ Psc
| ζ Psc
| ζ Psc
| style="color: gray;" | ζ Psc
| style="color: gray;" | ζ Psc
| style="color: gray;" | ζ Psc
| style="color: gray;" | ζ Psc
|-
|4th
| style="color: gray;" | μ Psc
| μ Psc
| μ Psc
| style="color: gray;" | μ Psc
| style="color: gray;" | μ Psc
| style="color: gray;" | μ Psc
| style="color: gray;" | μ Psc
|-
|5th
|ν Psc
|ν Psc
|ν Psc
|ν Psc
|ν Psc
|ν Psc
|ν Psc
|-
|6th
|ξ Psc
|ξ Psc
|ξ Psc
|ξ Psc
|ξ Psc
|ξ Psc
|ξ Psc
|-
|7th
|α Psc
|α Psc
|α Psc
|α Psc
|α Psc
|α Psc
|α Psc
|}

=== Maps (Gallery) ===
{| class="wikitable"
! colspan="3" |Historical Maps
|-
|[[File:Waiping in Cheonsang Yeolcha Bunyajido.png|alt=Waiping in Cheonsang Yeolcha Bunyajido|thumb|Waiping in ''Cheonsang Yeolcha Bunyajido'']]
|[[File:Waiping in Suzhou Star Map.png|alt=Waiping in Suzhou Star Map|thumb|Waiping in Suzhou Star Map]]
|
|}
Nandou in Suzhou Star Map
== IAU Working Group on Star Names ==
In 2026, the name of the historical constellation "Waiping" was suggested to be used for one of the stars in this constellation. Since '''δ Psc''' is the determinative star of it, then this name should be applied to δ Psc.

Decision: ... 

==References ==
[[References (Chinese)]]


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