A big name on a plain mountain
Xu is an earthly branch, the dog, the evening hours from seven to nine. Its band runs from 292.5 to 307.5 degrees, earth among the five phases, the first of the three Qian trigram mountains, Xin before it, Qian after. A grave that sits Xu faces Chen at 120 degrees.
The name is the largest thing about this bearing. Kui leads the Dipper, and students once prayed to it before exams. The school keeps that as imagery and no more. On the ring it is an ordinary star on a mountain with no rank, so the reading rests on what the eye finds on the ground.
Confirming, not lifting
If the range comes in through Xu, the first question is whether it is alive: does it rise and fall, throw off branches, narrow before the head. If yes, the school notes a Xu range under Tiankui and moves on to the cave. If no, the star is not mentioned.
A peak on Xu seen from the cave is read the same way. Upright, full and facing the site, it is a good sha and Tiankui confirms it. Water from Xu is judged on how it bends and where it leaves. The Cui guan pian matches stars to the dragon, cave, sha and water chapters, and in each the star is read after the ground; an ordinary star adds no weight of its own.
What this means on the ground
Tiankui sits on the Tianxing ring between Tianyi on Xin and Tianjiu on Qian. At a grave, stand behind the stone, sight along its face, level the plate and turn the line to each peak on the west by north west. From 292.5 to 307.5 the peak is on Xu. Read three times, then walk to the peak and look at it.
At a house or shop, stand inside the door, back to it. On the Xu bearing, note the nearest tall thing and the furthest. A quiet hill or a solid building there is good. A junction pouring traffic at the door, a pylon, or a tower with a blade like edge is a poor sha, and the Dipper's name does not soften it.
Common mistakes
Using a phone compass for the ring: it reads a bearing, not a star, and the pairing is this school's own. Reading Kui as a forecast of exam results: the school has no such reading; no star is read for a result at all. Counting stars and skipping the walk: a Xu peak that looks fine from the cave can be a landfill or a cut slope from the other side. Working off a map: the screen shows true north, the needle magnetic north, and the Xu band is only 15 degrees wide.
Questions people ask
What is the Tiankui star in feng shui?
The Tianxing star on the Xu mountain, 300 degrees west by north west. The name points to Kui, the first star of the Northern Dipper, with the imagery of exams and leading. An ordinary star that confirms the landform.
Is a house facing north west good?
A house that sits Xu faces Chen, south east. Good or not depends on what is in front and behind, not on the sitting mountain's name. Open ground in front, gathered water and a real back to lean on count for far more than the star.
Can a good star fix a bad plot?
No. In the Tianxing school the sky answers the ground. A flat, broken or cut range on Xu stays a poor range with Tiankui written over it. If the ground fails, choose another plot or another sitting, not a rescue from the ring.
Bring the bearings and photos of your plot to Master Zhang for a reading, or learn to walk a range yourself on the Ganzhou field course.