Instituto Brasileiro de Geografia e Estatística

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Geodesy

SIRGAS - Processing Center

Introduction

One of the main responsibilities of SIRGAS is the definition and materialization of a geodetic reference frame for the Americas. This is made possible through the establishment of a Reference geodetic network – a task assigned to the Work Group I (Reference Network). In order to achieve that purpose, two GPS measurement campaigns, one in 1995 to establish the SIRGAS95 Network and the other in 2000 to establish the SIRGAS2000 Network, were conducted.

Given the rising number of permanent GNSS stations in the American continent over the last years, the WG I (Work Group I) created the SIRGAS-CON Reference Network, which comprises the permanent GNSS stations of the Latin American and the Caribbean networks. In the WG I meeting, on May 2008, a proposal for the organization of the SIRGAS-CON Network was presented and accepted. It involved the following components: Local Operational Centers or data centers, Local Processing Centers, Combination Centers and the Network Coordinator. Most of these components existed, but it was necessary to coordinate several activities and the responsibilities of each part. It was also necessary to subdivide the network in sub-networks so that information would be processed by more than one center , enabling a redundancy in the solutions and a better analysis of the results.

Presently (July 2014), the SIRGAS-CON Network includes approximately 300 stations located in Latin America, the Caribbean Islands and Antarctica, encompassing:

I - A continental coverage network (SIRGAS-C) weekly processed by DGFI, in the analysis center called IGS-RNAAC-SIR (IGS Regional Network Associate Analysis Centre for SIRGAS). This Network evidences the densification of ITRF in Latin America.

II - National reference networks (SIRGAS-N), which densify the continental network and are calculated by the Local Processing Centers of SIRGAS, namely:

  • a) CEPGE (Ecuador)
  • b) CNPDG-UNA (Costa Rica)
  • c) CPAGS-LUZ (Venezuela)
  • d) IBGE (Brazil)
  • e) IGAC (Colombia)
  • f) IGM-Cl (Chile)
  • h) IGN-Ar (Argentina)
  • i) INEGI (Mexico)
  • j) SGM-Uy (Uruguay)

Both the continental and national networks share the same quality attributes and each station is analysed by three processing centers. Those Centers generate loosely contrained weekly solutions of the SIRGAS-N. Later, those solutions are combined with those of the continental network SIRGAS-C so that velocity and positions are determined for all stations. IBGE and DGFI carry out those tasks and the results become available to the public through the server ftp.sirgas.org. The constrained weekly solutions are referred to the epoch of observation and to the ITRF in force, presently the IGS08 - an accomplishment of the ITRF2008.

Processed Stations

The stations under the SIRGAS-CON network are provided with dual-frequency equipment and stable structures on top of which forced centering devices are installed.

Further information on the configuration of a SIRGAS-CON station can be found at Installation Guide for IRGAS-CON Stations.

Information on each one of the stations can be seen at: ftp://ftp.sirgas.org/pub/gps/DGF/station/log