Galactic Quadrant Coordinate System

The **Galactic Quadrant Coordinate System** (abr. **GQCS**) was the primary cartographical system used by the United Federation of Planets for astronavigation and sector classification. It was also referred to as **Okuda-Sternbach Notation**. (TNG: "The Price"; *Star Trek: The Next Generation Technical Journal*; *TNG Technical Manual*; *Star Trek: Star Charts*; *Star Trek: Pendragon*)

The GQCS developed from earlier systems in use by the United Earth and the Vulcans in the 22nd century. In this system, the Milky Way galaxy was first divided into four galactic quadrants – Alpha, Beta, Gamma and Delta – and from there, classified into smaller regions such as subquadrants, sector blocks and sectors. (TNG: "The Price"; *Star Trek: The Next Generation Technical Journal*; *TNG Technical Manual*; *Star Trek: Star Charts*)

Another system was created at the founding of the Federation, oriented around a Central Navigation Beacon, though it fell into disuse by the end of the 23rd century. (*Star Fleet Technical Manual*; *Star Trek Maps*; *Star Trek VI: The Undiscovered Country*)

## Sector classification and designations

Under the GQCS, each sector of the galaxy was designated with a nine-character alphanumerical sequence, such as "Sector 150225712". In common practice, the first four digits are normally omitted.

### Subquadrants

The first digit (or letter) in a sector's designation refers to its **subqudrant**, a wedge-shaped slice of the galactic disk. There are 36 subquadrants, designated 0 through 9, then A through Z. Each subquadrant is 50,000 light-years long, 3,6000 light-years high, and 8,727 light-years across at its widest point (at the galactic rim).

### Sector Zones

The second digit refers to a **sector zone**, a concentric circle 5,000 light-years wide and 3,600 light-years high centered on the galactic core. There are 10 sector zones, numbered 0 through 9.

### Sector Grids

The area of where a subquadrant and sector zone intersect is called a **sector grid**. Each grid is 5,000 light-years long by 3,600 light-years high. Its width varies with its distance from the galactic core. Most of local space around the UFP is within Sector Grid 15 (subquadrant 1, sector zone 5), which is roughly 4,500 light-years across at its widest point.

### Sector Quads

A sector grid is then divided into 100 **sector quads** of equal volume, numbered 00 through 99. The third and fourth digits in a sector's designation represent its sector quad. Sector quads are sometimes mistakenly referred to as "quadrants."

In UFP-local space, sector quads are 1,000 light-years long, by roughly 900 light-years wide, by 800 light-years high; closer to the galactic center, they will resemble wedges rather than cubes; and closer to the rim, the volume of space within each quad is larger.

### Sector Blocks

Every sector quad contains 900 to 1,000 **sector blocks** (or "Sectors", with a capital "S"), numbered 000 through 999. The next three digits in a sector's designation represent its sector block.

Around Federation space, sector blocks are exactly 100 light-years long, by approximately 100 light-years wide, with a height of precisely 80 light-years. They are laid out in a 9 x 10 x 10 grid in stead of 10 x 10 x 10 so that each sector within the block will be as close to perfectly 20-light-year cubes as possible. Farther out from the galactic center, the width of a sector block increases from 9 sectors to 10 (or more).

### Sectors

Finally, each sector block is divided into 100 actual **sectors**, numbered 00-99. The sector number denotes the final two digits of the sector designation.

Sectors are exactly 20 light-years long, by exactly 20 light years high, by approximately 20 light-years wide. Thus, near the UFP, each sector resembles a perfect cube 20 light-years on a side. The slight curvature is almost imperceptible because of the galaxy's immense size.

In and around Federation space, a typical sector contains about 40 stars, two-thirds of which are members of multiple star systems. Sectors within Star clusters would contain many more stars, perhaps hundreds or thousands; whereas in voids between the galaxy's spiral arms, a sector might contain no stars at all. (*Star Trek: Star Charts*)

Because most of explored space is contained within the sector grids immediately surrounding the Federation, the grid and quad are typically omitted, and the sector is referred to by the last five, or even last two digits of its designation. The last five digits will always be unique within a distance of at least 800 light-years in any given direction, and the last two digits will always be unique within at least 80 light-years. Thus an unwieldy "Sector 150225712" becomes "Sector 25712" or simply "Sector 12". (*Star Trek: Star Charts*; TNG: "Aquiel")

## Proper names and other conventions

While every sector of the galaxy has a GQCS designation, in common practice many sectors are called by a proper name. Sector names used by the Federation are typically either adopted from the local inhabitants, or based on the sector's primary star or other notable feature. As such, a single sector may be known by several names. The above "Sector 12" is more commonly called the "Deneva sector". (*Star Trek: Pendragon*)

Additionally, many of the core sectors of the Federation are known by old Earth designations that have no relation to the GQCS, but are numbered in the order in which they were explored by humans. For example, the Sol sector is most commonly known as "Sector 001," while Sector 002 contains the Alpha Centauri system, and the Vulcan sector is sometimes called "Sector Five."

Groups of up to 8 adjacent sectors may occasionally be referred to as "blocks" or "quadrants", like the Morgana Quadrant, though should more likely be called "octants." Alternately, a sector may be subdivided into sections known as "quadrants," though again, these should properly be referred to as "octants." (TNG: "Where Silence Has Lease"; *Star Trek: Pendragon*; *Star Trek Concordance*)

Sectors around the Romulan Neutral Zone are sometimes known by their United Earth designations from the period of the Earth-Romulan War, such as Foxtrot sector, Sierra sector or Tango sector. (*Star Trek: Star Charts*)

Some sectors, like Sector 221-G or Sector 39J may have additional characters in their designation, perhaps as a result of incorporation from other coordinate systems. (*Star Trek: New Frontier*, TOS: "The Immunity Syndrome", et. al)

## Background

* While the GQCS name and abbreviation were created for *Star Trek: Pendragon*, the sector system outlined here was devised by Geoffrey Mandel for his reference book *Star Trek: Star Charts*, based on the typical sector designations used in the *Star Trek: The Next Generation* era. "Okuda-Sternbach Notation" is *Pendragon'*s homage to Michael Okuda and Rick Sternbach who codified the four galactic quadrants in TNG during the early 1990s.

## See also

* Quadrant
* Sector
* Category:Sectors

## External links

* Star Trek: Star Charts article at ***Memory Alpha***, the canon *Star Trek* wiki.
* Astronomical coordinate systems article at ***Wikipedia***, the free encyclopedia.
* Galactic coordinate system article at ***Wikipedia***, the free encyclopedia.