While on a deer hunt, I woke with stomach trouble at about 3:30AM. I exited my vehicle to walk to the slit trench. As I sat (sorry), I observed a black triangle dart across the rims of the canyon we were camping in. Object made no sound. I seemed to not even care, got up and went back to my vehicle. Months later, I recalled the hunting trip and remembered the event. My actions that night were uncharacteristic, as I have looked to the skies my whole life and never witnessed a UFO before. Why then, when I finally saw something I could not explain, did I brush it off as nothing? However, I do remember not wanting to see it come back as I fell asleep that morning. The direction of flight was perpendicular to the NE-SW running canyon. I projected the speed to be about 500MPH at an altitude of 1000FT AGL. Object appeared to be between 50-75FT of equal length sides. No lights. If it had not been for city light pollution on an overcast sky, I would not have noticed the object. The object made no sound whatsoever. Incident occurred near Willcox, AZ. See details in map sketches. I am a trained Meteorological Observer from the military. I know our traditional aircraft. This was not one of them. The other people I camped with slept through the entirety of the event.