Ephemeris generation of the Galilean moons by using VLBI observations in support to stellar occultations

Stellar occultations are the most accurate Earth-based astronomy technique to obtain the lateral position of celestial bodies, in the case of natural satellites, their accuracy also depends on the central body to which the satellite orbits. The main goal of this thesis work is to analyze if and how very long baseline interferometry (VLBI) measurements of a body like Jupiter can be used in support to stellar occultations of its natural satellites by reducing the planetary uncertainty at the time of the occultation. In particular, we analyzed the events of the stellar occultations of Callisto (15.01.2024) and Io (02.04.2021). The stellar occultation of Callisto has been predicted and simulated using the stellar occultation reduction analysis (SORA) toolkit while the stellar occultation of Io has been already studied by Morgado et al. We then simulated the VLBI data of Jupiter according to the current JUNO trajectories. The required observation were then used as input of an estimation to which then we performed a covariance analysis on the estimated parameters to retrieve the formal errors (1 − σ uncertainties) at each epoch of the propagation. The results show that the addition of the VLBI slightly improves the uncertainty of Callisto even when Jupiter knowledge is worse while for Io we observed that the VLBI data is especially crucial in the scenario of an a priori uncertainty in Jupiter state of about 10km. Here we can have improvements of the estimated initial states of Io of about 70m, 230m and 900m to the radial, along-track and cross-track directions respectively. Moreover, we have also obtained the propagated errors of the two moons in terms of right ascension and declination which both show uncertainties in the mas level at the occultation time. Finally, we simulated Io and Europa together and we observed that at the time of the stellar occultation of Europa the along-track component of Io is constrained, confirming the coupling between the two inner moons.

L'influenza della preferenza manuale nell'interpretazione di conferenza: un contributo sperimentale

This study is based on a former student’s work, aimed at examining the influence of handedness on conference interpreting. In simultaneous interpreting (IS) both cerebral hemispheres participate in the decoding of the incoming message and in the activation of the motor functions for the production of the output signal. In right-handers language functions are mainly located in the left hemisphere, while left-handers have a more symmetrical representation of language functions. Given that with the development of interpreting skills and a long work experience the interpreters’ brain becomes less lateralized for language functions, in an initial phase left-handers may be «neurobiologically better suited for interpreting tasks» (Gran and Fabbro 1988: 37). To test this hypothesis, 9 students (5 right-handers and 4 left-handers) participated in a dual test of simultaneous and consecutive interpretation (CI) from English into Italian. The subjects were asked to interpret one text with their preferred ear and the other with the non-preferred one, since according neuropsychology aural symmetry reflects cerebral symmetry. The aim of this study was to analyze:1) the differences between the number of errors in consecutive and simultaneous interpretation with the preferred and non-preferred ear; 2) the differences in performance (in terms of number of errors) between right-handed and left-handed, both with the preferred and non-preferred ear; 3) the most frequent types of errors in right and left-handers; 4) the influence of the degree of handedness on interpreting quality. The students’ performances were analyzed in terms of errors of meaning, errors of numbers, omissions of text, omissions of numbers, inaccuracies, errors of nexus, and unfinished sentences. The results showed that: 1) in SI subjects committed fewer errors interpreting with the preferred ear, whereas in CI a slight advantage of the non-preferred ear was observed. Moreover, in CI, right-handers committed fewer mistakes with the non-preferred ear than with the preferred one. 2) The total performance of left-handers proved to be better than that of right-handers. 3) In SI left-handers committed fewer errors of meaning and fewer errors of number than right-handers, whereas in CI left-handers committed fewer errors of meaning and more errors of number than right-handers 4) As the degree of left-handedness increases, the number of errors committed also increases. Moreover, there is a statistically significant left-ear advantage for right-handers and a right-ear one for left-handers. Finally, those who interpreted with their right ear committed fewer errors of number than those who have used their left ear or both ears.