and slightly less accurately, in the Song Huiyao. The last sighting was on 6 April 1056, after a total period of visibility of 642 days. This duration is supported by the Song Shi. The Song Huiyao by contrast mentions a visibility of the guest star of only 23 days, but this is after mentioning visibility during daylight. This period of 23 days applies in all likelihood solely to visibility during the day, which naturally was much shorter. Sources The Song Huiyao (literally "Collected important documents of the Song dynasty") covers the period 960–1220. Huiyao is a traditional form of history books in China which aimed mainly to preserve primary sources, and as such are important sources supplementing the official Twenty-Four Histories. The Song dynasty had a specific government department dedicated to compiling the Huiyao, and some 2,200 volumes were published in ten batches during the Song dynasty. However, most of these documents were lost by the time of the Qing Dynasty except for the synopsis and a relatively small portion preserved as part of the imperial Yongle Encyclopedia. In 1809, the portion preserved in the Yongle Encyclopedia was extracted and re-published as the Song Huiyao Jigao (the "draft extract of the Song Huiyao"). Subsequent scholars have worked on the project further and the current edition dates from 1936. This document recounts the observation of the guest star, focusing on the astrological aspect but also giving important information on the visibility of the star, by day and by night. The Song Shi is the official annals of the Song dynasty. Chapter 12 mentions the guest star, not its appearance but rather the moment of its disappearance. The corresponding entry dated 6 April 1056 indicates: In chapter 56 ("Astronomical treaty") of the same document, the guest star is again mentioned in a chapter dedicated to this type of phenomenon, this time focusing on its appearance, The Xu Zizhi Tongjian Changbian ("Long compilation of the continuation of the Zizhi Tongjian"), a book covering the period of 960–1126 and written 40 years or so later by Li Tao (1114–1183), contains the oldest Chinese testimonies relating to the observation of the star. It was rediscovered in 1970 by the specialist in Chinese civilisations Ho Peng Yoke and collaborators. It is relatively imprecise in the case of the explosion of SN 1054. A loose translation of what was stated: There is an account of the star