What is the object in the top left corner?
Apparently, according to the image description, an astronaut was standing up through an open hatch at the time with the other hatch door in view together with the L-Band Antenna on the docked Agena vehicle and a blue 70mm UV camera on a neck strap in the foreground.
I think the photo was taken by an astronaut from outside the Gemini spacecraft so this is not a reflection on a window. The black horizontal line at the top of the photo that cuts across the top left of the object is the edge of the frame.
Source: https://tothemoon.ser.asu.edu/gallery/Gemini/11/Hasselblad Super-Wide Camera 70 mm
Blow-up
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