The H⁺₃ Latitudinal Profile of Saturn

Abstract

We present an H⁺₃ latitudinal profile of Saturn, obtained in 1998 October using the CSHELL spectrometer on the NASA Infrared Telescope Facility. The profile, measured at 3.953 μm, shows that the majority of the emission is concentrated in the auroral ovals, making Saturn similar to Jupiter and different from Uranus. The spatial resolution is sufficient to resolve the southern auroral oval, currently fully displayed around the south pole, into two peaks separated by 1.2". At the time of the observations reported here, the emission flux in the H⁺₃ line is 8.3(+/-1.7)×10^-18 W m^-2 for the intensity integrated over a 1.0" swath along the southern aurora and 5.8(+/-1.3)×10^-18 W m^-2 for the northern aurora. There may also be some mid- to low-latitude emission, similar to that on Jupiter. We suggest that planetwide H⁺₃ emission from Saturn is between 1.2 and 3.6×10¹¹ W.