Accuracy and Stability Assessment of the ILRS Stations Over Two Decades

Abstract

The development of the ITRF depends on the quality of the contributions from the four geometric techniques. With the GGOS requirements for ITRF accuracy and stability becoming exceedingly stringent, ITRS requests that each technique generate and deliver an assessment of the performance of each system over time, covering as much of the period spanned by their contribution as possible. Since the ITRF relies on the combination of the techniques at the co-located sites, this information can be used to sort out cases where a discrepancy is observed between the techniques and the local survey information, isolating the most likely culprit and taking appropriate steps to avoid distorting the final result. In response to an ITRS request we have developed a historical qualification index based on the long-term and short-term performance information available to ILRS, a consistently-derived set of systematic error estimates from the analysis of LAGEOS and LAGEOS 2 SLR data and all the engineering information reported to ILRS by the stations. We propose to establish and maintain this index to serve as input to ITRS for the ITRF2013 development as well as for the future realizations.