i put out my dogs at around 9:30pm. if the night is clear i look up at the evening sky. my attention was drawn to a white flash of light to my right. at first i thought it might have been a blinking star, airplane lights or helicopter. it was none of these. i kept focus on the spot in the sky where i thought i saw the light. around 10-seconds later it flashed again. best description i can give is, it was like someone turning on a flashlight in the sky, then turned it off. it was that bright. it repeated itself around 15-seconds later, same spot, no movement. i usually go outside with a flashlight to make sure my dogs don't stray too far away. so, i decided to flash it with my flashlight. when i did, it immediately responded! i did this numerous times and each time it replied. to test my assumption, i stopped flashing (signaling) with my flashlight. it would not respond at that point but would then flash every 15-20 seconds on its own. i should point out it made no sound. i had a strong sense it was really high in the sky. to test my conclusions again, i asked my wife to come outside to see what i was seeing. she was surprised to see every time i would signal with my flashlight it would reply, to the point it made her nervous and asked me to stop. i should point out the object was stationary during the event, and not visible to the eye. you could only sense its shape when it flashed the white light, which by the way, the size of the light was way bigger than the biggest star in the sky; my guess, 4-5 times bigger. the object was clearly very high in the sky since i could see aircraft fly beneath it. between flashes near the end of the event i could tell the object changed position in the sky. between flashes it was moving east but very slow, then it disappeared and stopped flashing. event lasted roughly 20-minutes. by the time i decided to take video with my phone, the object had left.