the large Kuiper belt object , which displays apparent signs of water ice, Huya's spectrum appears redder and featureless, suggesting that its surface is covered with a thick layer of tholins concealing water ice underneath. It is thought that the layer of surface tholins on Huya is thicker than that of Varuna, as a result of a more intense radiation environment. Best-fit models for these absorption features suggest that Huya's surface consists of a mixture of cometary ice tholins (ice tholin II), nitrogen-rich Titan tholins, as well as water ice. Spectrographic observations of Huya's spectrum with the Very Large Telescope in 2001 and 2002 have tentatively identified weak absorption features at near-infrared wavelengths around 0.6–0.82 μm, possibly indicating the presence of phyllosilicate materials on its surface. The 0.6 μm absorption feature in Huya's spectrum resembles those in the spectra of stony S-type asteroids, which may suggest the presence of spinel group minerals, albeit in trace amounts as such minerals are unlikely to be abundant in trans-Neptunian objects. Other absorption features near 0.7 μm in Huya's spectrum appear akin to those in the spectra of dark asteroids, indicating the presence of hydrous silicate minerals such as phyllosilicates, which may have been aqueously altered through heating induced by impact events or the radioactive decay of radionuclides in Huya's interior. However, later observations of Huya's spectrum did not find any absorption features related to aqueously altered material, suggesting that they are likely concentrated in a small, localized area of Huya's surface. Brightness Huya has a visual absolute magnitude (H) of 5.04 and a low geometric albedo of 0.083. Its apparent magnitude, the brightness as seen from Earth, varies from 19.8 to 21.6 magnitudes. Huya comes to opposition in June of each year at a visual apparent magnitude of 19.8. At wavelengths of the R-band range, Huya appears brighter in red light, with its R-band apparent magnitude reaching 19.11 magnitudes at opposition. At the time of Huya's discovery, it was thought to be one of the brightest trans-Neptunian objects known, which corresponded to an initially large size estimate for Huya as it appeared relatively bright for a distant object. As Huya comes to opposition, its brightness increases as a result of an opposition surge, in which its phase angle approaches zero. In 2001, long-term photometric observations of Huya were conducted to observe its opposition surge behavior and attempted to identify any indication of variability