to the north of the Three Stars asterism, the composition of which is well known, corresponding to the bright stars of Orion, its possible localisation is strongly restricted to the immediate proximity of the star ζ Tauri, located between "Five Chariots" and "Three Stars". This star, of medium brightness (apparent magnitude of 3.3), is the only star of its level of brightness in this area of the sky (there is no other star that is brighter than an apparent magnitude of 4.5 within 7 degrees of ζ Tauri), and therefore the only one likely to figure among the asterisms of "Shi Shi". All of these elements, along with some others, allow "Tianguan" to be confirmed beyond reasonable doubt as corresponding to the star ζ Tauri. Position relative to Tianguan Three Chinese documents indicate that the guest star was located "perhaps a few inches" South-East of Tianguan. Song Shi and Song Huiyao stipulate that it "was standing guard" for the asterism, corresponding to the star ζ Tauri. The "South-East" orientation has a simple astronomical meaning, the celestial sphere having, like the Earth's globe, both north and south celestial poles, the "South-East" direction thus corresponding to a "bottom-left" location in relation to the reference object (in this case, the star ζ Tauri) when it appears at the South. However, this "South-East" direction has long left modern astronomers perplexed in the context of this event: the logical remnant of the supernova corresponding to the guest star is the Crab Nebula, but it is not situated to the southeast of ζ Tauri, rather in the opposite direction, to the northwest. The term "perhaps a few inches" (ke shu cun in the Latin transliteration) is relatively uncommon in Chinese astronomical documents. The first term, ke, is translated as "approximately" or "perhaps", the latter being currently preferred. The second term, shu, means "several", and more specifically any number between 3 and 9 (limits included). Finally, cun resembles a unit of measurement for angles translated by the term "inch". It is part of a group of three angular units, zhang (also written chang), chi ("foot") and cun ("inch"). Different astronomical documents indicate without much possible discussion that a zhang corresponds to ten chi, and that one chi corresponds to ten cun. The angular units are not the ones used to determine stars' coordinates, which are given in terms of du, an angular unit corresponding to the average