Imperial Astrography

The methods by which the stars are mapped are collectively referred to as the field of Astrography, in the same fashion that terrestrial mapping is known as Cartography. The field of Astrography is based around a few central concepts: the standard Stellar directions, the division of space into Sectors, Subsectors and Systems, and several other such concepts which this Primer will, in an attempt to prepare you for more intense study in the field, inform you of. Please note, the Primer in Stellar Mapping is not intended to be a stand-alone text, but rather serve as an introduction and refresher on the basics of this field.

Stellar Directions

Core Reference Navigation

The standard method of navigation in the three-dimensional plane that is space is to use the Galactic Core as the prime reference point. The Core Reference method has four defined directions: Coreward, Rimward, Spinward and Trailing.

Coreward refers to travel inward towards the Galactic Core, while Rimward refers to travel that takes you out towards the Galactic Rim. Spinward means in the direction in which the galaxy rotates, while Trailing is moving against that motion.

As a note, amongst some citizens of the Third Imperium, Coreward takes on a second meaning, instead referring to the Imperial Core, on Earth. While this should be obvious from context, be aware that this second definition does exist and is in usage.

In-System Navigation

Navigation on a Systemic scale, rather than Galactic, uses slightly different terminology. Unlike on a Galactic scale, it is generally possible to establish a "plane" which everything in-system operates in reference to - this is known as the Ecliptic. System North, or Up, is moving upwards of the Ecliptic plane, while System South, or down, is moving downward in reference to the Ecliptic. In-System is moving towards the star at the center of a system, while Out-System is moving towards the Systemic Rim. Of course, this is merely a rough approximation of actual navigation. For a more in-depth examination and discussion of the mechanics and mathematics of stellar navigation and course-plotting, please see your textbook.

Astrographic Notation, Terms and Methods


A Domain, under the control of an Archduke, the highest rank of Nobility shy of the Emperor himself, is the largest unit of measurement in Astrography, and also the most fluid. While each contains roughly 6 Sectors in theory, some of the existing seven Domains are large enough to extend past the borders of the Imperium itself. The Domain is, in any coordinate string, the first digit, and is expressed by number, from 1 to 7.


A Sector is defined as a cluster of 16 Subsectors, and is usually (within the Third Imperium) under the purview of a Sector Duke, second-highest ranking of the general Nobility. Few individuals living within a given Sector will actually leave its borders, and among those that do, the majority already lived within a border system and were able to easily enter the territory of another Sector. Each Sector is referred to by a 4 number string - the number of the domain in which it is located, when it was mapped in respect to the other known Sectors, its distance from the Imperial Core on Terra, and the year in which it was discovered. For instance, the Coreward Reach, south-most Sector of the Imperium, is referred to as


A segment of space 8 parsecs by 10 parsecs large (a Parsec is roughly 3.26 light years in size), and the general scale in which a map of an area is presented, each Subsector is ruled by a Duke - one of which for each Sector is also the Sector Duke. Each Subsector within a given Sector is assigned a five digit alphanumeric string, generated mostly randomly. The first digit of each string, however, is the letter a Subsector is assigned in reference to its position within the greater Sector, from A to P. For instance, Yggdrasil Subsector in the Coreward Reach is known as B3PZ9. Expressed in full, the coordinates of the Halish subsector would be As must be clear already, astrographic coordinates become very complicated the more exact the location indicated, and as such will never enter most casual settings.


Lastly, the Star System is the smallest Astrographic unit of measurement available. (Astrographic units of measurement refer to the scales a given map can show, rather than Stellar units, which measure actual distances in space). The coordinates for a given Star System are expressed as the hexadecimal information string of the main planet in that system. The capital system of the Coreward Reach, Jormungandr, is therefore located at 0304-ADFFCA5-14, or, in full:

In-system, the same coordinate method is also used, but the hexadecimal notation for the planet being indicated is used, if that planet is not the main world.

Reading a Subsector (Or Sector) Map

A subsector map, through use of a few standardised symbols, expresses a great deal of information about a given system while requiring the smallest space per system to do so. The symbols and their meanings are found here.

The larger circle at the center indicates the presence of a planet - if it is filled, there is water present. If it is not filled, there is no water present.

Star/Triangle: A star indicates a Naval base, a triangle indicates a Scout base.

A, B, C, D, E, and X: These indicate the quality of the Starport on the main world of that system.

Small dot: A gas giant is present in-system.

Amber/Red Circle: A dotted amber circle within the hex indicates an Amber Travel Zone is in effect - travel within the system is undertaken at the risk of the pilot alone. A solid red circle, on the other hand, indicates a Red Zone. Travel within the system is forbidden and trespassers risk fatal retaliation from the in-system guards if they enter.

The system name itself also provides some information. A name in all capitals, for instance PRIMUS, means that the main world of the system has a population in excess of 1 billion. A name expressed normally, such as Secundus, means the main world has a population lower than 1 billion.

A diagram will eventually be forthcoming, but as of this printing the funding required to requisition a graphics artist has been denied five times, despite the fact that textual representation alone is insufficient to properly explain this particular subject. The author withholds his opinion of his superiors in regards to this.

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