Astrometric observations and analysis of Triton during 2013–2019

Triton is the largest irregular satellite of Neptune. A total of 1135 new observed positions of Triton in the period 2013–2019 were collected by the 1.0 m telescopes at Yunnan Astronomical Observatory of CAS during 13 nights. These positions of Triton were obtained based on Gaia DR2 catalogue. We compared our observations to the theoretical positions retrieved from IMCCE ephemeris online service with satellite ephemeris of Emelyanov et al. (2015) model and planetary ephemeris EPM2017. The result shows that the mean residuals are −5 mas and − 2 mas in right ascension and declination, the standard deviation of residuals are 31 mas and 29 mas in right ascension and declination. Such seven-year time span observations with high precision will provide data support for the development of orbit theory of Triton.