UFO Sighting in Death Valley, California on February 20th 2016 – a light in the sky every ten seconds,

I was camping outside of Death Valley for spring flowers. it was about 11pm-12am spent the evening looking at the stars, and the occasional satellite overhead. There where some small aircraft flying with their tell tale beacons flashing, which I have seen thousands of times. during this star gazing. I noticed a craft traveling slowly in a northeast direction. 75-80 degrees in the air. It had a light pattern I have never seen before. It would pulse a light every 10 seconds, and it did not flash like a traditional aircraft beacon. it was like it was on a dimmer switch being toggled on. The duration of the pulse was about 2-2.5 seconds. after observing this pulse a couple of times, I noticed that when the light was off I could faintly observe that the craft was a darkish grey to the black background of the night sky. I watched this craft for about 2 minutes. It never strayed from its course or changed speed while on course My question are there private/commercial aircraft that have this type of light pattern?