Airborne and Ground Observations of the Stellar Occultation by Triton on 5 October 2017

On 5 October 2017, Triton occulted the 13^th magnitude star UCAC4 410-143659 as seen from the Eastern US, North Atlantic, and Europe. Our collaboration observed this event from the Stratospheric Observatory for Infrared Astronomy (SOFIA) aircraft, as well as numerous (over two dozen) ground stations throughout the US and Europe. Here, we present the preliminary results of analyzing this dataset and highlight a number of features of Triton's atmosphere. Initial reduction of the data indicates that the atmospheric pressure increases seen throughout the 90's have stabilized or perhaps begun to reverse, as the current pressures are more comparable to those measured during the earlier occultations of the 1990's than the later ones, although still greater than the pressure observed by Voyager 2 in 1989. Careful calibration of the multi-wavelength observations made from SOFIA indicates a clear atmosphere at the levels to which we are sensitive (>35 km), with no signs of the various particulate dust plumes or cloud-like structures seen by Voyager 2 below 8 km altitude. Data reduction is progressing and a final report is in preparation.