English: The image shows a B-17 Flying Fortress bomber as seen from another B-17's H2X display.
The H2X was a ground-scanning radar used by the USAAF in the late WWII period. It was a development of the British H2S using a new magnetron that worked in the X-band rather than the S-band. This gave the H2X higher resolution, enough to make a clear image of an aircraft in this case.