The Chronologue Celestial Coordinate System¶

Astronomical coordinate systems are used for specifying positions of celestial objects relative to a given reference frame, based on physical reference points available to a situated observer. The Chronologue Celestial Coordinate system (CCCS) is an astronomical coordinate system used exclusively by the Chronologue. As the Chronologue can “hop” from one point to another, the CCCS was developed to describe navigation that uses a series of directions rather than a single direction with a static starting point.

The CCCS is similar to a travel itinerary. It describes a destination point, a period of time spent at the destination point, and then describes another destination point. This repeats until the final destination is reached.

Once the Chronologue has deployed a miniature wormhole within the gravitational influence of an object, the wormhole will exist in a relative position to the object and can be traced backwards and forwards through time.

The basis of the CCCS is that any object at any point in time can be used as the origin of a new vector pointing to another object.

Background¶

Existing astronomical coordinate systems use the Earth (geocentric) or the Sun (heliocentric) as the origin point and indicate a specific direction to a specific object. This does not function appropriately for the Chronologue as the Chronologue is capable of viewing objects at any time, including events that predate or postdate the existence of the Earth or the Sun.

Traditionally an astronomical coordinate system is used to describe the location of specific astronomical objects within a specific context. Using a specific origin point, an astronomical coordinate system uses a center point, a fundamental plane, and direction to indicate the location of an object.

The design of these astronomical coordinate systems are based on the original use cases of these systems. Historically, astronomical coordinate systems were used in astronomy to define the locations of astronomical objects. Even with significant investment in spacefaring technology, the Earth remains the origin point for nearly all space missions, or destinations can be plotted using existing coordinate systems in series. This makes a complex coordinate system like CCCS unnecessary for any practical use outside of the context of the Chronologue.

Use cases¶

The CCCS is fundamental to the operation of Octavia’s Chronologue. Without the CCCS, the Chronologue would not be able to view objects more than one “hop” away from the Chronologue.

Examples¶

Consider the following example, where the Chronologue is navigating to Object C:

To find Object C using the CCCS:

At time_t(g) a set of coordinates (x1 and y1) are followed from Object A (the Earth) to find Object B.
The Chronologue’s wormhole stays in proximity to Object B while time passes.
After a specific amount of time passes (time_rp(h)), a new set of coordinates (x2 and y2) are followed to find Object C.

To represent this in a data structure used by the Chronologue’s API:

{
    "name": "Object B",
    "location":  { 
        "path_0": {"x": "x1", "y": "y1", "distance": "r_prox", "time_r": "g"},
    }

    "name": "Object C",
    "location":  { 
        "path_0": {"x": "x1", "y": "y1", "distance": "r_prox", "time_r": "g"},
        "path_1": {"x": "x2", "y": "y2", "distance": "r_prox", "time_r": "h"}
    }
}

Comparison to other astronomical coordinate systems¶

Coordinate system	Center point (origin)	Fundamental plane (0° latitude)	Poles	Latitude	Longitude	Primary direction (0° longitude)
Horizontal (also called alt-az or el-az)	Observer	Horizon	Zenith, nadir	Altitude (a) or elevation	Azimuth (A)	North or south point of horizon
Equatorial	Center of the Earth (geocentric), or Sun (heliocentric)	Celestial equator	Celestial poles	Declination (δ)	Right ascension (α) or hour angle (h)	March equinox
Ecliptic		Ecliptic	Ecliptic poles	Ecliptic latitude (β)	Ecliptic longitude (λ)
Galactic	Center of the Sun	Galactic plane	Galactic poles	Galactic latitude (b)	Galactic longitude (l)	Galactic Center
Supergalactic		Supergalactic plane	Supergalactic poles	Supergalactic latitude (SGB)	Supergalactic longitude (SGL)	Intersection of supergalactic plane and galactic plane
Chronologue Celestial Coordinate System	Center of the Earth, the relative position around another body	Celestial equator	Celestial poles	Declination (δ)	Right ascension (α) or hour angle (h)	March equinox or origin direction

Major differences¶

The most significant difference between the CCCS and other coordinate systems is time, and the lack of a fixed origin point for any vector after the first.