I was a passenger in a pick-up truck going to photograph a friend on her quad 4x4 at a local sand pit and noticed wonderful clouds to photograph complimented with a setting sun just as we were outside of town. i did not notice the object till after i came home to process that evening's photographs. at around the 7-8pm location on this one photograph i noticed an aberration not evident on the images before or after this image. i did check my camera also for any dirt or smudge on the lens, inside mirror & sensor of digital camera (canon 7d). it was rectangular and somewhat blurred shape (brownish/black w/apparent clear heat trail. my camera settings were in manual at f11 & 1/250 sec. iso auto because of the brightness of the sky and setting sun.