What observatory is XXX associated with?
Makemake
Combining the detection in infrared by the Spitzer Space Telescope and Herschel Space Telescope with the similarities of spectrum with Pluto yielded an estimated diameter from 1,360 to 1,480 km. From the 2011 stellar occultation by Makemake, its diameter has been measured to be (1502 ± 45) × (1430 ± 9) km. This is slightly larger than Haumea, making Makemake likely the third largest known trans-Neptunian object after Pluto and Eris.