It allows the caster to track a magic item from the astral side using the item's astral signature. If not blocked by other spell such as Protect, this spell reveals the item's exact location. Distance is not a factor, but the caster must know the astral signature well, which means that he had to study the item in the past.
kanatanaru ASUTORARU no umi ni fukabishimono yo
sono kage wo ware ni arawase
You, who is floating far away on the astral sea;
Show your reflection to me