Objectives Based on the first asteroid exploration plan announced by China Space Administration on April 19, 2019, the main belt comet 133P/Elst-Pizarro (7968) is one of the possible mission targets. We aim to report integrated orbital fits for 133P through all the available ground-based optical data.
Methods We developed an optical orbit determination software and compared it with the well-known OrbFit software system. The 133P/Elst-Pizarro's ground-based optical observation data from July 24, 1979 to October 28, 2019 were analyzed. In addition, we carried out a simulation orbit determination analysis aimed at 133P/Elst-Pizarro to discuss the orbit determination accuracy from ground-based optical data.
Results After the fitting process, the residual distribution of 133P ground-based optical data is consistent between our results and the results from OrbFit. The measurement statistical residual root mean square (RMS) is less than 0.01″, and the internal coincidence accuracy of orbit determination is also consistent with each other. In our simulation experiments, we used 20-year simulation optical observation data measured once a month from Yunnan station and Chile station. The data were also added with Gaussian white noise which is close to the current actual observation level. The results of our simulation experiments reflected that the optical orbit determination accuracy of the asteroid was at 50 km level.
Conclusions The processing results of 133P optical data suggests the reliability of our software. Further simulation analysis shows that the optical orbit determination accuracy of the asteroid can be effectively improved by increasing the observation data or reducing the observation noise.
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