31st Annual Meeting of the DPS, October 1999
Session 55. Dust and Rings Posters
Poster Group II, Thursday-Friday, October 14, 1999, , Kursaal Center

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[55.04] Three Stellar Occultations by the Saturn System in 1998

R. G. French (Wellesley C.), J. Harrington, P. D. Nicholson (Cornell U.), B. Stecklum (Max Planck Inst.), B. Sicardy, F. Lacombe (Obs. de Paris), K. Matthews (Caltech)

We observed three stellar occultations by the Saturn system during the 1998 opposition, with the goals of obtaining stratospheric temperature profiles from the atmospheric events and constraints on Saturn's pole direction and ring geometry from ring event times. On 29 September, Saturn occulted GSC 0630-00405 (K=8.8), which we observed from the Calar Alto 3.5m telescope using the MAGIC infrared array camera at \lambda=2.2 \mum. We succeeded in recording the immersion atmospheric event, but the seeing was poor (3.5''), making it difficult to separate the stellar flux from sunlight reflected from the rings. We observed the 5 October occultation of GSC 0623-01090 (K=9.4) from three stations. At Calar Alto, observing conditions were quite good and we recorded the egress ring/atmosphere event at 2.2 \mum. Egress was also observed from the Palomar 5m with an IR camera at \lambda=3.44 \mum to reduce the ring background to about 10 times the unocculted stellar flux. At ESO, the 3.6m telescope was equipped with the Adonis adaptive optics system and the Sharp II IR camera in the K band. Ingress and egress ring and atmosphere events were observed under excellent conditions. Finally, the 14 Nov occultation of GSC 0622-00345 (K=8.4) was observed from the IRTF using NSFCAM. We obtained a very high SNR atmosphere immersion light curve in the K band, and observed ring egress with a 3.255 \mum filter designed to reduce reflected sunlight from both the planet and the rings. We will present results of the atmospheric occultations, and a progress report on the analysis of ring events.

This work was supported in part by NASA Grant NAG5-4046.

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