Research on the Centering Algorithm of Dwarf Planet Haumea System

Affected by the Earth's atmosphere, the image of primary and satellite system observed by ground-based telescopes often appears unresolved. Therefore, there may be some deviation between the system photocenter and the center of mass. The accurate measurement of the center of mass is helpful to improve the orbital parameters and to reveal the formation and evolution of the solar system. Taking the dwarf planet Haumea and its brighter satellite Hiíaka as an example, we simulate its motion of the photocenter around the center of mass and explore whether the track of photocenter is the same with different seeings. The simulation results show that when using the two-dimensional Gaussian centering algorithm, the photocenter track is changing with the change of seeing, however, this phenomenon will not occur when using the modified moment centering algorithm. Based on the simulation results and the influence of noise, a new centering algorithm is proposed in this paper, which can effectively reduce the influence of changing seeing on the accurate photocenter position measurement. In addition, we also consider the influence of primary's changing luminosity on the photocenter position measurement. The images of dwarf planet Haumea were observed over 29 nights from February 7, 2022 to May 25, 2022 by three telescopes located in Yunnan Province. Our results show that the fitted error of the new centering algorithm's results is smaller than the two-dimensional Gaussian algorithm's results. In addition, we find that theoretical position of the bright satellite from Jet Propulsion Laboratory (JPL) and Institut de Mécanique Céleste et de Calcul des 'Ephémérides (IMCCE) ephemeris has a large deviation.