A pulsing light that flashed regularly every 10 seconds; both the speed of the pulsing and intervals in between were consistent.

While observing the stars with the naked eye up in the mountains away from the city and minimal light pollution, we observed a pulsing/flashing light roughly 20 degrees above Jupiter and Venus. The light would pulse to just a bit brighter than a star then fade away to nothing. It was a quick pulse and the time between flashes was roughly 10 seconds; it was a consistent gap of time between flashing intervals.  It remained stationary in the sky and continued this behaviour for about 5 minutes, after which it didn’t appear again.