[3][4] On July 1, 1819, Johann Georg Tralles in Berlin observed a brilliant comet low in the sky during the evening twilight.

On July 3, Friedrich Georg Wilhelm von Struve measured the nucleus at 8″ with a tail of several degrees.

[3] Also on July 3, François Arago used a polarimeter of his own invention to analyze the light from the comet's tail and discovered that it was polarized.

Johann Wilhelm Pastorff [de] noted that he saw on that day a round nebulousity with a bright spot near its center and made a sketch of it.

[8] Historian Nathaniel Philbrick writes about the great comet seen in July 1819 by the people on the island of Nantucket, Massachusetts in his 2000 book, In the Heart of the Sea.

[9] The comet was observed by the Stephen Long expedition to the Great Plains from near present day Jefferson City, Missouri.