By their calculations, at the closest approach, its speed approaches 8% of the speed of light. That's so fast that time dilation comes into play. An hour at S62 would last about 100 Earth minutes.
Rather than being a simple ellipse, it follows a spirograph motion by which its orbit precesses about 10 degrees with each cycle. This kind of relativistic precession was first observed with the orbit of Mercury, but only as a small effect.
This is super cool! Make sure to click through and look at the pretty pictures!