NASA GSFC/JCET ILRS Analysis Center Contribution to ITRF2020-u2025 Development

The NASA GSFC/UMBC Joint Center for Earth Systems Technology (JCET) ILRS Analysis Center supports the International Laser Ranging Service (ILRS) through routine SINEX submissions, network validation, and contributions toward future updates of the International Terrestrial Reference Frame (ITRF). As an ILRS Analysis Center (AC) and the designated ILRS backup combination center (ILRS-B), JCET/NASA GSFC generates daily and weekly SINEX solutions and combines contributions from eight ILRS ACs to produce the ILRS-B solution, complementing the official ILRS-A solution provided by ASI for the ITRF Combination Centers (DGFI, JPL & IGN).

Since LARES-2 was launched in August 2022, ILRS Analysis Centers began generating v90-format solutions in April 2025, retroactively covering data from September 2022. These solutions incorporate LARES-2 tracking using the new Data Handling Format (DHF), improving geodetic coverage and supporting future reference frame updates. The v90 series will be reprocessed to apply updated mass corrections, include newly available stations, and reinstate sites previously quarantined during earlier processing cycles. This v90 SINEX will represent the core of our contribution to the development of ITRF2020-u2025, which will be based on a full reprocessing of SLR data from 2021.0 to 2026.0

In this paper, we provide information on the v80 & v90 series that contribute to this ITRF contribution. We summarize the impact of adding LARES-2 compared to the legacy geodetic satellite contributions from LAGEOS-1,2 and Etaton-1,2. We review the performance of the ILRS-B combination, in particular with respect to the station coordinates and Earth Orientation Parameters (EOPs).