An Improved High-precision Ephemeris of Nereid from Quality-controlled Multisource Observations and Refined Dynamical Modeling

Abstract Precise orbit determination and high-accuracy ephemeris calculation for Nereid are crucial for understanding the dynamical origin of its high-eccentricity orbit. This study adopts a refined dynamical model that incorporates the gravitational influence of Kuiper belt objects, and consolidates multisource data from Voyager 2, Gaia FPR, and ground-based optical observations. A strict quality control procedure is implemented by combining an Isolation Forest outlier detector with a knee-point-based adaptive threshold to define the rejection criterion. This study employs a strict quality control procedure to ensure the use of high-quality data, resulting in a more accurate orbit solution. Compared with the latest IAA2025 ephemeris within the same analysis framework, our solution exhibits significantly reduced formal uncertainties. At the reference epoch of 2007 January 1 (TDB), the derived initial orbit has 1 σ position uncertainties of 9.505 km, 8.740 km, and 9.097 km in the x , y , and z components, respectively, and velocity uncertainties of 0.779 mm s −1 , 1.729 mm s −1 , and 0.928 mm s −1 in v x , v y , and v z . This improvement reflects the enhanced precision achieved through improved quality control and the incorporation of additional ground-based observation data. Over a 100 yr integration, the maximum position deviation is 1004.650 km, and the maximum velocity deviation is 1183.966 mm s −1 , compared to NEP097.