Navigating in space is a surprisingly challenging affair. While one is rarely concerned about running into some unmapped planet, simply navigating by dead reckoning is a recipe for disaster.
A well surveyed system will have orbital datasets for all of its components, right down to most of the asteroids, but this is by no means complete. No matter their best efforts, every survey team misses some asteroids thanks to their odd orbits, material composition and just plain bad luck. With this orbital data, a ship can easily plot a course to their destination, taking into account the motion of any orbiting bodies.
But wait, if it’s so easy to plot a course with easily accessible data, what’s the problem? The issue isn’t where everything else is, but where the ship is instead. If your position is incorrect, a well-charted asteroid may actually be on a collision course with your ship. A good sensor watch may catch this in time to prevent disaster, but depending on the closing velocity, this is not always guaranteed.
There are several ways to work out a ship’s location without any external assistance. Using several known pulsars, it’s possible to lock down a ship’s location to within a few kilometers after only a few hours. Additionally, it’s also possible to work out your location by taking sightings of various orbital bodies, though this method can leave you open to larger errors (you did remember to take into account light lag, yes?)
You might already be seeing a few issues with these methods however. Sighting pulsars requires an x-ray telescope, which isn’t exactly standard gear on many commercial starships, and that’s assuming you already know what directions to look! Fixing your location by taking sightings of several planets requires the use of a visible spectrum telescope. A more common piece of kit to be sure, but most commercial ships only have one or two at most. Additionally, these methods are only as good as the crew doing the measurements, and they rely on having the time and expertise to take a proper reading. Onboard computers and navigational software can do much, but the old rule of garbage in, garbage out still applies. Finally, they also rely on having accurate navigational data. Not always guaranteed, and not always available!
So, a quick mention of survey ships before we get back to the way this problem is handled. Survey ships obviously see completely new star systems on a regular basis. Part of the initial survey is to map exactly where in the galaxy the star system is. For this they make use of several x-ray telescopes to observe several pulsars at once. Combined with a stellar database, this identifies a star system precisely. In the process, the survey ship is also capable of using these pulsars to precisely place itself in the star system.
But what about ships that aren’t dedicated survey ships? Well, if the star system is expected to see any kind of commercial traffic, the survey flotilla has one more task to complete. When the other survey work is completed, the flotilla deploys a quartet of navigational buoys in the star system. Each of these buoys radiates an omnidirectional radio pulse that can be detected by any ship near the primary star. Each buoy has a unique identifier signal, made of the star system’s navigational ID and its position in the system.
The messages are encoded in a basic binary signal, instead of a more technically complex amplitude or frequency transmission system. Each pulse starts with a single long “beep”, followed by 1 to 4 beeps (1 beep is the star zenith buoy, 2 is the nadir, 3 is the coreward, and 4 is the rimward buoy). Following that is the binary system identifier. There is then a period of quiet, and then the signal repeats. For systems with multiple stars, each component is assigned its own identifier. As an example, Alpha Centauri would be classified as three separate star systems (Based around Alpha Centauri A, Alpha Centauri B, and Proxima Centauri)
In a star system with only one star, two buoys are laid at the nadir and zenith points of the star, far enough away to be at a gravitationally stable point (a standard distance several dozen AU at a minimum, but this can depend on the star system). Another two are placed in the Oort cloud, directly coreward and rimward in the star system. These four signals are enough for any ship to precisely pin their location in the star system. Binary systems will instead just have nadir and zenith buoys at both of their stars. For systems with three or more stars, nadir and zenith buoys are emplaced at all the stars, with additional coreward and rimward buoys wherever needed (and gravitationally stable).
Each of the buoys themselves are filled with redundant systems and substantial hardening to survive anything short of deliberate damage or a direct hit by some extrasolar object. Powered by an array of RTGs, the buoys have an expected service life of over 150 years each. Even if they are abandoned and fail, it is expected that they will remain in place for hundreds of years longer, if not even more. As these buoys are not located at warp points or other strategically important locations, concealment is not a concern.
In star systems that are on main travel routes, or habitable star systems, additional options are available. An inhabited planet puts out a phenomenal radio signature, which makes accurate lock-ons with a directional radio antenna a very simple task. In addition, these star systems may have one or more communication stations at warp points in the system. These stations also have a navigational beacon as part of their design.
While this system is specifically used by the deWulf Corporate Democracy, similar systems have been put into place by most other starfaring nations.