1 Introduction

We initiated an astrometric program of observations of natural satellites in 1982. Considering that, up to accuracies better than $0{\hbox{$.\!\!^{\prime\prime}$}}15$, only a few hundred positions of Triton, were published since the discovery of this satellite by Lassel in 1846 (see for instance Jacobson et al. 1991), we began our observations of this satellite in 1985.

The first results of our observations, presenting 53 photographic positions distributed along 13 nights, between 1985 and 1988, were presented in Veiga et al. (1995). A second paper with 433 CCD observations of Triton obtained in the period 89-94 over 29 nights was published in the following year (Veiga & Vieira Martins 1996, hereafter called Paper I).

 

Figure 1: The distribution of the observations, both photographic and using CCDs

In this paper we present 759 CCD observations obtained in 1995, 96 and 97, distributed over 35 nights. We then compare the whole set of our measured positions of Triton related to Neptune to the positions calculated using the parameters given by Jacobson et al. (1991). The distribution of our CCD observations of Triton are presented in Fig. 1. In Sect. 2 of this paper we describe the observations, the measures and the reduction procedures. In Sect. 3 we compare our results with theoretical calculated positions and in Sect. 4 a conclusion is presented.