An astrogator was was a specialist in navigating a spaceship through the Matrix.
Navigational tables provided a starship’s commander with basic instructions, but the Matrix through which she guided her bubble universe could not be directly sensed. An astrogator used the minute rise and fall in mast charges to plot variations in the Matrix and the corresponding change in the ship’s relation to the sidereal universe.
A really successful astrogator had a sense that, like perfect pitch, went beyond skill and training. That astrogator’s mind saw into the matrix. His runs were faster, his planetfalls more precise, and when he voyaged beyond the existing charts he brought his ship back.1:1
Ship navigation through the Matrix used Sailing Directions and astrogation computers, but talented astrogators could improve directions by judging energy gradients with a precision that the Sailing Directions, which were simply data compiled from averages, and astrogation computers could not equal.6:27
Rather than having a separate specialist, the captain and all watch-standing officers on RCN vessels were expected to be astrogators. Skill levels, of course, differed.
Some of the best known astrogators included: