The SIRGAS multi-year solutions provide the most accurate and up-to-date SIRGAS station positions and velocities. They are used for the realization and maintenance of the SIRGAS reference frame between two releases of the ITRF. While a new ITRF release is published more or less every five years, the SIRGAS reference frame multi-year solutions are updated every one or two years. The combined adjustment is done with the program ADDNEQ2 of the Bernese GNSS Software V5.2 and it is based on the loosely constrained weekly solutions (SINEX files) submitted by the IGS RNAAC SIRGAS to the IGS Analysis Centres. The computation includes the identification of position discontinuities due to episodic events such as co-seismic displacements or antenna configuration changes, in order to set up the appropriate parameters in the adjustment. The station positions (associated to a reference epoch) and velocities are estimated by aligning the SIRGAS reference frame to selected ITRF stations existing in the region. The SIRGAS multi-year solutions released so far are:
SIR17P01 horizontal (left) and vertical (right) velocities. Taken from Sánchez L. (2017) SIRGAS reference frame realization SIR17P01, Technische Universitaet Muenchen, Deutsches Geodaetisches Forschungsinstitut DGFI-TUM, IGS RNAAC SIRGAS, supplement to: Sánchez L. (2017) Kinematics of the SIRGAS reference frame, Symposium SIRGAS2018. Mendoza, Argentina. November 28, 2017.