Time Taken: One minute when your position is known and you are following a commonly-travelled jump route for which hyperspace coordinates have already been calculated (can be reduced to one round in emergencies). A few hours when your position is known, but your destination is one to which you have not travelled before and the nav computer must calculate coordinates. One day when you must take readings to determine your ship's current position and then compute hyperspace coordinates.
Starship pilots use astrogation to plot a course from one star system to another. Astrogations can be used to shave time off of a jump in SW: Dark Dreams.