We observed the 2018 August 4 stellar occultation by the Kuiper Belt object (486958) 2014 MU69, the first close flyby target of the extended New Horizons mission. Rather than capture a solid-body occultation by the KBO itself, our program aimed to constrain the opacity of rings, moons, or other debris in the nearby environment. We used the Hubble Space Telescope Fine Guidance Sensors (HST FGS) instrument in TRANS F583W mode to collect 40 Hz time resolution photometry of the stellar occultation star for one HST orbit during this observation. We present the results of reduction and calibration of the HST FGS photometry, and set upper limits on τ of ∼0.02-0.08 for rings or other dust opacity within the Hill sphere of (486958) 2014 MU69 at distances ranging from ∼1660 to ∼57,700 km from the main body.
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