I see now, I was calculating the temperature at the subsolar point, they are averaging over a uniformly illuminated sphere. Since the illuminated side is a dis

I see now, I was calculating the temperature at the subsolar point, they are averaging over a uniformly illuminated sphere. Since the illuminated side is a disc with area pi x R^2 and the sphere has surface area 4 x pi x R^2 we need to include a factor of 1/4: (6.11e7*(1-0)/(4*1*5.670373e-8))^.25 = 4051.281 K