Astrometric results of the mutual events between the Saturnʹs satellites observed at Yunnan Observatory

The mutual eclipse of S4 Dione by S3 Tethys (Dec 23, 2009) and mutual occultation of S3 Tethys by S4 Dione (Apr 24, 2010) were observed at Yunnan Observatory during the international campaign in 2009–2010. The aim of this paper is to calculate the astrometric data of the involved Saturnian satellites during the mutual events, using a same dynamical model as proposed by Assafin et al. (2009) for the mutual occultation and a same one as proposed by Zhang and Liu (2011) for the mutual eclipse, and taking the scattering properties of the Saturnian satellites surfaces into account. Compared with the theory TASS 1.7 (Vienne and Duriez, 1995), the O–C(x) and O–C(y) are 10.1 mas, 3.4 mas for the mutual eclipse S4 by S3 and 28.4 mas, −1.3 mas for the mutual occultation S3 by S4, and with respect to the theory by Lainey et al. (2011), the results are 1.0 mas, −5.0 mas and −0.2 mas, 2.5 mas respectively.