During Space Shuttle Atlantis flight STS-46. an object can be seen in background moving horizontally and then upwards.

As can bee seen in accompanying Youtube video: 
an object can be seen in background moving from left hand side to the screen to the right hand side and then moving upwards.
An important caveat: At one point a flock of birds, spooked by the noise of the space shuttle, flies towards the left hand side of the image. By doing so, the birds appearance obscure the image of the object previously stated. Thus the object is clearly in the background and not something on the camera lens, which could be thought of as an explanation due to its erratic movements.
-Points of Interest in Video pertaining to unknown object:
-29 second mark: Appearance of object can be seen as video moves away from rockets firing to a broader frontal view of the Shuttle
-33-34 second mark: Flock of birds moving across the vantage point from left of center to right shows the unknown object is in the background
-35 second mark: unknown object moves upwards enough to escape camera shot
Thanks for your time.