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According to Phys.org's New Horizons team prepares for stellar occultation ahead of Ultima Thule flyby:

"Gathering occultation data is an incredibly difficult task," said New Horizons occultation event leader Marc Buie of the Southwest Research Institute, Boulder, Colorado, who also discovered Ultima Thule about a year before New Horizons flew past Pluto in July 2015. "We are literally at the limit of what we can detect with Hubble and the amount of computer processing needed to resolve the data is staggering."

The final occultation observations of Ultima Thule are scheduled for Aug. 4 in Senegal and Colombia, with Buie again leading the effort. "Our team of almost 50 researchers using telescopes in Senegal and in Colombia are certainly hoping lightning will strike twice and we'll see more blips in the stars," he said. "This occultation will give us hints about what to expect at Ultima Thule and help us refine our flyby plans."

Question: Is this an occultation of two different objects that are very close together, so that one is observed in Senegal and the other in Columbia, or is it the same occultation, with the shadow moving from one place to another?

For background see Timing shadows from the Kuiper belt! Any news? Did it work? as well as How (the heck) can 2014 MU69's orbit be know well enough for a close flyby by New Horizons?, and answers therein.

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Is this an occultation of two different objects that are very close together, so that one is observed in Senegal and the other in Columbia, or is it the same occultation, with the shadow moving from one place to another?

It is the occultation by Ultima Thule of one star, seen from different locations.

This is the shadow's path across Earth:

enter image description here

By choosing a number of observation locations, they can create a rough map of what UT will look like. From the NH press briefing on Jan 2, here's that map, updated with a photo of Ultimate Thule:

enter image description here

Like the earlier observations, the 2018 occultation campaign observed the occultation from multiple places to increase the chance of getting a good observation.

A photo of Ultima Thule from the JHUAPL site:

LORRI image of Ultima Thule

The new images — taken from as close as 17,000 miles (27,000 kilometers) on approach — revealed Ultima Thule as a "contact binary," consisting of two connected spheres. End to end, the world measures 19 miles (31 kilometers) in length. The team has dubbed the larger sphere "Ultima" (12 miles/19 kilometers across) and the smaller sphere "Thule" (9 miles/14 kilometers across).

The team says that the two spheres likely joined as early as 99 percent of the way back to the formation of the solar system, colliding no faster than two cars in a fender-bender.

Here's a more detailed occultation map showing all of the observation tracks:

enter image description here

Despite some digging, I haven't found which stars were used for these observations.

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