The ILRS ASC Contribution to ITRF2020: A Sneak Preview

The International Laser Ranging Service (ILRS) Analysis Standing Committee (ASC) plans to complete the re-analysis of the SLR data covering the period 1983 to end of 2020 by the end of 2020. This will ensure that the ILRS contribution to ITRF2020 will be available to ITRS in early 2021, as agreed by all space geodetic techniques answering its call. In preparation for the development of this contribution, the ILRS completed the re-analysis of all data (1983 to present), based on an improved modeling of the data and a novel approach that ensures the results are free of systematic errors in the underlying data. Since the completion of ITRF2014 the ILRS ASC, devoted almost entirely its efforts to develop, evaluate and implement a new approach in monitoring and modeling systematic errors. A Pilot Project initially demonstrated the robust estimation of persistent systematic errors at the millimeter level, leading us to adopt a consistent set of a priori corrections for data collected in past years. The current reanalysis used these corrections, leading to improved results for the TRF attributes, reflected in the resulting new time series of the TRF origin and scale. The ILRS ASC is now using the new approach in the development of its operational products and as a tool to monitor station performance, extending the history of systematics at each station that will be used in future re-analysis. The new operational products form a seamless extension of the re-analysis series, providing a continuous product based on our best knowledge of the ground system behavior and performance, without any dependence whatsoever on a priori knowledge of systematic errors (although information provided by the stations from their own engineering investigations are always welcome and taken into consideration). With all but the last year (2020) included in this product that spans 37 years, we can now generate a nearly final version of the ILRS contribution and illustrate the benefits to the ITRF from the new approach. The presentation will demonstrate the level of improvement with respect to the previous ILRS product series and give a glimpse of what is to be expected from the development of a preliminary version of the ITRF2020.