New Horizon’s First Glimpse of Ultima Thule

The New Horizons spacecraft has caught its first glimpse of its next flyby target, the Kuiper Belt object nicknamed Ultima Thule, a bit more than four months ahead of its New Year’s Day close encounter. The image on the left is a composite produced by adding 48 different exposures from the News Horizons Long Range Reconnaissance Imager (LORRI), each with an exposure time of 29.967 seconds. They were taken on 16 August. The predicted position of Ultima Thule is at the center of the yellow box as indicated by the crosshairs. It’s just above and left of a nearby star that is approximately 17 times brighter than Ultima Thule. On the right is a magnified view of the yellow box that has been processed by subtracting the background star field a recorded by LORRI in September, 2017, well before before it could detect the Ultima Thule itself. The small Kuiper Belt Object is clearly visible in this star-subtracted image and is very close to where the mission navigation team predicted, indicating that New Horizons is on course.

The many artifacts in the star-subtracted image are caused either by small mis-registrations between the new LORRI images and the template or by intrinsic brightness variations of the stars. At the time of these observations, Ultima Thule was was roughly 6.5 billion km from the Sun, and New Horizons was around 172 million km from Ultima Thule.

Image Credits: NASA / JHUAPL / SwRI

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