An ancient book of astronomy - Towne of Rune, Secret Chamber in Museum.
A set of star charts - Old Stargazer Clan Hall, Minimal level to enter hall is 50. Note: The star charts that are an astral do NOT work.
Then visit a venerable veteran in Palace of Diocletian, sayto him "work" and give him the items in the order he asks for in the order he asks for them.