About SIRGAS

The original acronym of SIRGAS (Geocentric Reference System for South America) changed in 2001 to Geocentric Reference System for the Americas following the recommendation of the 7th United Nations Cartographic Conference for the Americas (New York, January 22 – 27, 2001) to adopt SIRGAS as the reference system in all American countries. In 2020, the acronym of SIRGAS changed again to Geodetic Reference System for the Americas, as the objectives of SIRGAS were extended to the determination of a unified physical reference system for gravimetry, physical heights and geoid. This change is in agreement with the recommendations arisen from the International Workshop for the Implementation of the Global Geodetic Reference Frame in Latin America, held in Buenos Aires, Argentina, in September 2019.

All official matters related to SIRGAS are available at https://sirgas.ipgh.org/.

SIRGAS as geocentric reference system is defined identical  to the International Terrestrial Reference System (ITRS). Its realization is a regional densification of the global International Terrestrial Reference Frame (ITRF). The reference station positions are associated to a specific (reference) epoch and their variation with time is taken into account by discrete station velocities or by a continuous velocity model, which comprises tectonic plate movements and crustal deformations. Realizations or densifications of SIRGAS associated to different reference epochs and referring to different ITRF solutions materialize the same reference system and, after reducing their coordinates to the same frame (ITRF) and reference epoch, they are compatible at the cm-level. The extension of the SIRGAS frame is carried out by national densifications of the continental network, which serve as local reference frames.

The geographical coordinates are derived by applying the parameters of the GRS80 ellipsoid.

The activities related to realization and maintenance for the geocentric reference system are coordinated by the SIRGAS-WGI: Reference System.