QSO B0839+187 (PKS 0839+187) is a quasar that was used for a VLBI experiment conducted by Edward Fomalont and Sergei Kopeikin in September 2002. They claimed to measure the speed of gravity, but this is disputed.
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This article is an automated import of the Wikipedia article "QSO B0839+187", available at https://en.wikipedia.org/wiki/QSO_B0839%2B187 . Text is licensed under CC BY-SA 4.0.