Great Comet of 1811 - Observations

Observations

From May to August, the comet's position made it difficult to spot because of its low altitude and the evening twilight. Both Flaguergues and Olbers were able to recover it in Leo Minor during August, Olbers noting a small but distinct tail, consisting of two rays forming a parabola, when viewing through a comet seeker. By September, in Ursa Major, it was becoming a conspicuous object in the evening sky as it approached perihelion: William Herschel noted that a tail 25° long had developed by October 6.

By January 1812, the comet's brightness had faded. Several astronomers continued to obtain telescopic observations for some months, the last being Vincent Wisniewski at Novocherkassk, who noted it as barely reaching an apparent magnitude of 11 by August 12.

The Great Comet of 1811 was thought to have had an exceptionally large coma, perhaps reaching over 1 million miles across—fifty percent larger than the Sun. The comet's nucleus was later estimated at 30–40 km in diameter and the orbital period was calculated at 3,757 years (later adjusted to 3,065 years). In many ways the comet was quite similar to Comet Hale-Bopp: it became spectacular without passing particularly close to either the Earth or the Sun, but had an extremely large and active nucleus.