We present time-resolved near-infrared ( J and H ) photometry of the extreme Kuiper belt object ( 136108 ) Haumea ( formerly 2003 EL _ { 61 } ) taken to further investigate rotational variability of this object .
The new data show that the near-infrared peak-to-peak photometric range is similar to the value at visible wavelengths , \Delta m _ { R } = 0.30 \pm 0.02 mag .
Detailed analysis of the new and previous data reveals subtle visible/near-infrared color variations across the surface of Haumea .
The color variations are spatially correlated with a previously identified surface region , redder in B - R and darker than the mean surface .
Our photometry indicates that the J - H colors of Haumea ( J - H = -0.057 \pm 0.016 mag ) and its brightest satellite Hi ’ iaka ( J - H = -0.399 \pm 0.034 mag ) are significantly ( > 9 \sigma ) different .
The satellite Hi ’ iaka is unusually blue in J - H , consistent with strong 1.5 \mu m water-ice absorption .
The phase coefficient of Haumea in the J -band is found to increase monotonically with wavelength in the range 0.4 < \lambda < 1.3 .
We compare our findings with other Solar system objects and discuss implications regarding the surface of Haumea .