Setebos (moon)

Setebos also known as is one of the largest retrograde irregular satellite of Uranus

Discovery and Naming

It was discovered on 18 July 1999 by John J. Kavelaars et al. and provisionally designated S/1999 U 1.
Confirmed as Uranus XIX, it is named after the god Setebos worshipped by Caliban and Sycorax in William Shakespeare's play The Tempest.
A crater on Umbriel is also named after Setebos, but with the spelling Setibos.

Setebos orbits Uranus at an average distance of 16,256,000 km, in 1978 days, at an inclination of about 152° to the ecliptic, in a retrograde direction and with a high eccentricity of 0.445. The orbital elements are continuously changing due to solar and planetary perturbations.

Setebos estimated diameter is 47 kilometers, assuming an albedo of 4%.
The satellite appears neutral in visible light, similar to Prospero.
Measurements of Setebos's light curve by the Kepler space telescope indicate that its rotation period is about 4 hours and 15,3min. which makes it one of the fastest-rotating moons in our solar system.

Setebos probably did not form near Uranus but was captured by Uranus later. The orbital parameters suggest that it may belong to the same dynamic cluster as Sycorax and Prospero, suggesting a common origin. However, Sycorax has a much redder color than the other moons, which tend to be gray in color.