MAGNA-SIRGAS (EPSG:4686)
Sep 24,2026

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Introduction

MAGNA-SIRGAS (EPSG:4686) is the latest geocentric geographic coordinate reference system officially adopted by Colombia. It is based on the GRS 1980 ellipsoid and referenced to the Greenwich meridian. It replaced the older Bogotá 1975 datum introduced in 1941, and uses longitude and latitude (in degrees) as coordinate units. It covers the entire territory of Colombia, including its associated islands and maritime areas, such as San Andrés, Malpelo, Roncador, Serrana, and Serranilla. This datum is the legal standard for surveying, GIS applications, and GNSS positioning in the country. While it is highly compatible with WGS84, it is not completely identical. Since 2018, it has been gradually replaced by the updated version MAGNA-SIRGAS 2018 (EPSG:20046).

Coordinate System Composition

Reference ellipsoid: Uses GRS 1980 (Geodetic Reference System 1980), with a semi-major axis of 6,378,137 meters and a flattening of 1/298.257222101. This defines the mathematical shape and size of the Earth.
Geodetic datum: The datum name is Marco Geocéntrico Nacional de Referencia (National Geocentric Reference Frame). Its origin is located at the Earth's center of mass, and its orientation is aligned with the International Terrestrial Reference Frame (ITRF). This ensures consistency with global geocentric coordinate systems.
Prime meridian: Uses the Greenwich meridian (0° longitude) as the reference for longitude, complying with international standards.
Coordinate system type: An ellipsoidal 2D geographic coordinate system, using geodetic latitude and geodetic longitude as coordinate axes, with directions north and east, respectively.
Units: Coordinate values are expressed in degrees, with an angular unit based on a conversion factor to radians of 0.0174532925199433.
Transformation relationship with WGS84: The TOWGS84[0,0,0,0,0,0,0] parameter indicates that there is no systematic offset from WGS84 under normal accuracy requirements. Therefore, they can be considered equivalent, although they are not strictly identical.
Coverage: Applies to the entire territory of Colombia (including land and maritime areas), and also covers associated regions such as the San Andrés y Providencia archipelago, Malpelo Island, Roncador, Serrana, and Serranilla.

Pros

High international compatibility: Adopts the GRS 1980 ellipsoid (semi-major axis 6,378,137 m, flattening 1/298.257222101), which is highly consistent in mathematical model with major global geodetic systems such as WGS84 and the ITRF framework. This facilitates international data exchange and interoperability.
Nationwide unified standard: Replaced older local datums such as Bogotá 1975 introduced in 1941, resolving data confusion caused by the coexistence of multiple coordinate systems within Colombia. It provides a unified legal framework for nationwide surveying, land registration, and GIS applications.
Easy GNSS applicability: The TOWGS84 parameter is [0,0,0,0,0,0,0], indicating no systematic offset from WGS84 within normal accuracy ranges. Therefore, GNSS devices such as GPS can be used directly in Colombia without complex transformations.
Scientifically sound as a geocentric positioning system: The datum origin is located at the Earth's center of mass, and its orientation is aligned with the International Terrestrial Reference Frame (ITRF). As a modern geocentric coordinate system, it has a scientific foundation and supports high-precision spatial data acquisition.
Complete coverage: Applicable to the entire territory of Colombia, including the mainland, the San Andrés y Providencia archipelago, Malpelo Island, Roncador, Serrana, and Serranilla, meeting national-level spatial reference needs.

Cons

No elevation information: It is a 2D geographic coordinate system (latitude/longitude on the ellipsoid) and does not include a vertical datum. Therefore, it cannot meet the high-precision elevation requirements of modern 3D engineering such as tunnels, bridges, and drone surveying.
Lagging in dynamic accuracy support: It does not integrate a dynamic crustal deformation model or a regional gravity field update mechanism. Because the South American Plate continues to move northwestward, long-term use without plate motion correction may accumulate centimeter-level positioning errors.
Superseded by a newer version: Since 2018, it has been officially replaced by MAGNA-SIRGAS 2018 (EPSG:20046). The newer version introduces the ITRF2014 framework, annual updates of station coordinates, and a more precise velocity field model, meaning EPSG:4686 has clear limitations in technical sustainability.
Not strictly WGS84: Although the transformation parameters are zero, it is not strictly identical to WGS84 by definition. In precision engineering and surveying such as high-precision reference networks and crustal deformation monitoring, additional corrections are still required, posing potential error risks.
Insufficient regional processing capacity: The local processing centers for the SIRGAS framework in Latin American countries are relatively underdeveloped, and data redundancy is insufficient. Ideally, each station should participate in computations from at least three processing centers; a lack of this may affect the continuous refinement and maintenance of the coordinate frame within Colombia.

Application Scenario

MAGNA-SIRGAS (EPSG:4686), as Colombia's legal national geographic coordinate reference system, is widely used in fields such as national surveying, cadastral registration, urban planning, and real estate management. In addition to providing a unified spatial positioning standard for government agencies and enterprises, it is also the core coordinate framework for Colombia's geographic information system (GIS) construction, natural resource surveys, environmental monitoring, and infrastructure development including roads, water conservancy facilities, and energy pipelines. Furthermore, because of its high compatibility with WGS84, it is widely adopted in GNSS satellite positioning, aerial remote sensing image processing, and emergency disaster response, supporting the collection, integration, and sharing of various spatial data across Colombia from the national to the local level. Although the transition to MAGNA-SIRGAS 2018 is progressing gradually, it continues to be used for large volumes of existing data and applications that do not require high precision.