2004 DW: The largest Kuiper Belt Object?
Astronomers discover an icy world at the fringes of the solar system.
by Francis Reddy
Posted February 20, 2004
"Because astronomers know the distance to 2004 DW, its brightness should indicate its size relative to Quaoar if both objects reflect the same proportion of sunlight. At the moment, says Trujillo, 2004 DW appears to be about 870 miles (1,400 km) across, making it the new record holder. "We'll be attempting to measure that in the next week or two with the IRAM telescope in Spain," Trujillo adds. This is the same heat-sensitive telescope Trujillo and Brown previously used to refine estimates of Quaoar's size. In addition, the team will attempt to obtain images with the Hubble Space Telescope and, possibly, the Spitzer Space Telescope."
http://www.astronomy.com/Content/Dynamic/Articles/000/000/001/670eqmni.asp

Frequently Asked Questions About 2004 DW.
http://www.gps.caltech.edu/~chad/2004dw/

Perhaps using Spitzer they were able to determine it is darker than expected and therefore larger.

Bob Clark