Gigantict Disc with rotating side lights headed northeast over Kayenta into Monument Valley, UT.On December 10th, 2016, at approx. 18:45 hrs., a co-worker and I working at a secure site approx. 3 miles north of Kayenta, AZ, Noticed a series of parallel, pulsating lights in columns covering the entire horizon headed northeast toward Monument Valley, UT. The objects disappeared and then a gigantic disk shaped object rimmed with spinning lights appeared where the previous lights disappeared, also moving slowly in the same direction. The size of the object covered approx. 1/2 of the horizon and did not change size as it moved behind the mountain in the distance. Pre-paid Verizon mobile phone camera not powerful enough to capture anything but a bright planet. I drew pictures of the site and the craft on a piece of notepad paper. No cloud cover, clear sky, just after sunset.While sitting in my patrol vehicle at the secure site, my coworker exclaimed suddenly to turn out my lights and look behind me. I noticed the strange pulsating lights moving in an apparent formation to the north. We both exited our vehicles to watch the lights. They appeared to cover the entire horizon moving in alternating patterns. After approx. 3 minutes they all disappeared and at this time we noticed that new lights began to light up, one after another and begin to "spin" rapidly. Each individual light had a trail behind it, and was a blue flame color. As all of the spinning lights were lit a large "disc" shaped object became apparent. The lights all moved to the left, then right, then from the left side and right side to the center, then left and right again, in apparent patterns. The "disc" was so immense in scale I can only compare it to the ridiculous size of the craft in the movie independence day. We both realized its size because it ! took up approx. 1/2 of the horizon and its size did not change as it moved behind the mountain (mesa?). The entire event lasted approx. 10 minutes. At 18:52 I text messaged my mother to create a time stamp about halfway through the sighting.I have never seen a UFO, though I have seen recordings on the news and internet from time to time, etc. As I write this, almost 24 hours later, I am still shocked. I was an Uber-Skeptic...Reply by email and I can send illustrations if desired, and coordinates of my location at the time.