Program: GS-2021B-Q-133

Title:Stellar Occultation by Neptune system
PI:Felipe Braga-Ribas
Co-I(s): Gustavo Benedetti-Rossi, Bruno Sicardy, Damya Souami, Stefan Renner, Emmanuel Lellouch, Bruno Morgado, Rafael Sfair, Thamiris de Santana, Joana Marques Oliveira, Josselin Desmars, Thomas Seccull, Ricardo Salinas, Andrew W Stephens

Abstract

We propose to study the properties of Neptune's ring system by means of stellar occultation using from both Gemini North and South ('Alopeke and Zorro, respectively). The complete study of the Neptunian system dates back to Voyager in 1989. Stellar occultations (1983-1990) have allowed to discover the arcs (incomplete ring-like structure) and to probe the upper atmosphere of Neptune. A stellar occultation on Oct 7, 2021 is an oppotunity to measure (after over 30 years) the optical depth of the rings and constrain further the material's redistribution. As we need fast photometry with low time resolution, the selected instruments in Wide-Field mode, with a subarray of 512 and bin 2x2 will be suficient to obtain the required data. For better image contrast between Neptune and the star z'filter will be used.