A number of 2003 UB313 related news articles has come out in the past week, and Nature will have a paper published tomorrow regarding a size measurement using IR vs. visual albedo. 3000km+-400 diameter , roughly 10% error. It makes the albedo of 2003 UB 313 to be 60%, like Pluto. While many of the big KBOs are bright, not all of them are, and it remains an area of speculation. What's the albedo of crystalline water ice on Quaoar? Why is the bulk albedo of it only 12%? Small areas of fresh ice? Is there a resurfacing going on for the high albedo KBOs?
Meanwhile, ScienceNOW reports that Brown et al made a direct HST measurement of the disk, calling it just a touch over the diameter of Pluto at 2300km.
The naming of the KBO is stuck in international bureaucratic limbo, deep in committees that can't agree on a definition of what a planet is. It depends on what the definition of 'it' is. (I guess).
The satellite so far has only one observation of it published. As soon as a second image is taken and reduced, an accurate determination of the mass of 2003 UB313 can be made.