The diameter is estimated at 72 km ( assuming albedo of 0.04 ) , making it the second biggest non-spherical moon of Uranus , half the size of Sycorax , the biggest non-spherical moon of Uranus . Its diameter is estimated at 72 km ( assuming albedo of 0.04 ) making it the second largest irregular satellite of Uranus , half the size of Sycorax , the biggest irregular satellite of Uranus .