4 Conclusion

In this paper 2784 $(x,\,y)$ positions of the 4 largest Uranian satellites related to Oberon were presented. They are distributed over 35 nights. Putting these observations together with those we published in previous papers, we have 5528 $(x,\,y)$ observed positions distributed between 97 nights in the period 1983-1998. These positions were observed with the same telescope in very similar conditions. The accuracy of these observations is better than $0\hbox{$.\!\!^{\prime\prime}$}08$ for Miranda and $0\hbox{$.\!\!^{\prime\prime}$}05$ for Ariel, Umbriel and Titania. Therefore this sample is well qualified for use in future improvements in the of the Uranian system dynamics.

Acknowledgements

We want to thank A.H. Andrei for his comments and suggestions, and also thanks the CNPq-Brazil for partial support of this work.