While the image appears bright, the light is just reflected sunlight (from the earth, per the webcast). The circularization burn doesn't start until about T+ 00:55:16 per the SpaceX webcast. But at about T+ 00:52:58 it looks like an object produces a moving shadow that passes from left to right across the spacecraft. If so, what was it?
If the shadow is caused by blocking the light from the earth, then this puts constraints on its size.
