So, the balloon flies above 99.5% of the atmosphere, but the telescope hangs under the balloon, so it have to take photos more sideways than straight up? Got to be a lot more than 0.5% of the atmosphere in the frame then.
Good picture, but at least part of that length is yet-to-be-inflated balloon. I'm guessing that the thicker section is the canopy of the descent parachute, so everything above that is likely part of the balloon. Assuming it is, and the balloon inflates to a sphere with the top at the same height, it looks like the telescope can point about 60° above the horizon.