I've spent years looking at the sky and stars and know what an airplane looks like, satellite, and meteors. But I saw something different the other night: an object tracking south to north at a height I would have assumed to be a satellite. However, it was not continuously illuminated but pulsed about every 12 seconds and grew brighter for about 2 seconds then faded to dark. It continued to do this as it tracked across the sky in a straight line headed north. A few minutes later a faint satellite was seen moving north to south along a similar line with a constant illumination.
I looked up on a satellite tracking website and found the satellite moving north to south but nothing was recorded moving south to north overhead my location. I just never have seen one pulse - and the pulse increased in intensity during its duration then faded - repeating with each pulse.