Navigating

Imagine navigating across interstellar space on the basis of visual observations like the Kirkasanters in Poul Anderson's Technic History. Here is another example from the Psychotechnic History. Looking at a drawing, a Nomad captain says:

"'Let's see. The shiningness is a bright gaseous nebula, of course, and the remote spiral is probably the Andromeda galaxy. That very bright star can only be Canopus, if you're in the Cross region, and here's the same dent in the Milky Way you can see from here.' He gestured to a view-screen overhead, blackness and the ghostly bridge of stars." (The Peregrine, Chapter XII, p. 101)

So it is a bit like recognizing a landmark or a familiar mountain range.

(I must go to a party. The holiday season interrupts blogging.)

Later: The captain, giving the drawing to the astrogator, tells him to use all the star tables and computers to find that part of space as accurately as possible.