We presented 22 astrometric photographic positions of Helene. The observations of this satellite is very difficult. However, using special procedures and CCD detectors, we observed in the last years this satellite and also the Tethys Lagrangian satellites Telesto and Calypso. The results of these observations will be presented in a forthcoming paper.
Acknowledgements
The authors wish to thank Dr. R.A. Jacobson for the theoretical positions of Helene provided and the CNPq-Brazil for partial support of this work. C.H. Veiga would like to thank State of Rio de Janeiro Science Foundation - FAPERJ for providing computational facilities for this project.
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