Aircraft question

What type of aircraft would have a single light that gave off a slow blink?

Unlike airplanes which have that blink-blink affect, I saw an aircraft tonight around 9pm that had one single light, and a very bright one at that, that gave off a slow paced single blink, more of a bliiiiiink type if you see what I'm saying.

corporate jets or small pure jets have a single or less seen double landing light that can be seen for 110 miles
when they descend and point right at you!! blinking every two seconds or so.....more like on for a long second then off for a short second

Could you hear the engines? Military helicopters usually run with a solid red light or a slow blinking one at night. They have IR illuminators on them to allow the pilots to fly in close formation at night with a low/no light situation. Fighters on patrol sometimes only have one anti-collision light on especially when over CONUS to adhere to FAA law.