Ice Dragon (constellation)
On the way to Standfast with his squire, Aegon Targaryen, Ser Duncan the Tall looks up to the night sky and sees, among other constellations, the Ice Dragon. There are clouds in the north so the dragon's blue eye is obscured.
A Clash of Kings
A Storm of Swords
During their journey to the Wall, when Bran and his companions lost their way a few times, they needed only to wait for a clear cold night when the clouds did not intrude, and look up at the sky for the Ice Dragon. Bran remembers that the blue star in the dragon's eye points the way north, as Osha had told him once.
After helping Edric Storm escape to Essos and preparing to face down Stannis Baratheon about the matter, Davos Seaworth looks out the window of the Chamber of the Painted Table in Dragonstone and sees familiar stars, including the Ice Dragon. He hopes it means good luck.
The way's easy. Look for the Ice Dragon, and chase the blue star in the rider’s eye.