햇귀, haetgwi: the first light, the very first of it, as the sun comes up.
The faintest light of the day and the most definite. Nothing else is awake for it. It comes over the sill, gets onto the floor, and moves while you are looking at it — which no other light of the day will do for you.
By the time it has climbed the far wall it has turned into ordinary morning and you have stopped noticing it.
Fifteen minutes, at the outside.