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D.J. Osip, B.N. Hilbert, J.L. Elliot, M.J. Person (Department of Earth, Atmospheric, and Planetary Sciences, MIT), R.R. Howell (Univeristy of Wyoming), A.S. Bosh (Lowell Observatory)
On 1999 October 10, Jupiter occulted the star HIP9369 (V =7.6). The shadow of Jupiter's northern limb passed nearly tangent to the Earth's northern limb, providing a rare opportunity to probe Jupiter's northern auroral zone. Immersion occurred through the northern auroral oval along the dusk limb, while emersion occurred along the dawn limb, away from the auroral oval.
Here, we present analyses of successful observations of this occultation made from the Infrared Telescope Facility (IRTF) in Hawaii and the Wyoming Infrared Observatory (WIRO). At the IRTF, NSFCam was used in movieburst mode to record immersion and emersion lightcurves at a data rate of approximately 4 Hz, imaging a 20"x20" field of view at a wavelength of 2.12 microns. At WIRO, we imaged a slightly smaller field of view at 2.28 microns with a data rate of about 2 Hz. The conditions at both sites were photometric and additional near simultaneous observations of the auroral emissions were made to help determine the auroral activity level and spatial distribution. Using a newly developed ellipsoidal planetary atmosphere lightcurve model we derive the temperature profiles for the auroral and non-auroral atmosphere of Jupiter at the time of occultation. These occultation analyses are sensitive to several scale heights that include the microbar pressure level where the bulk of the auroral energy is deposited and where much of the ultraviolet, and visible auroral emissions occur. The results of this first occultation through the Jovian auroral region are compared with previously observed stellar occultations by Jupiter that probed equatorial and mid-latitudes.
This research was supported in part by NSF Grant # AST-0073447 & NASA Grant # NAG5-6826.