3 or 4 lights in a perfect triangle arrangement, to the west of Arlington.Two of us went outside at night to walk the dog. I was noticing the stars and that one in the clear western sky looked "odd". I kept looking at it and noticed it appeared to be not one light, but multiple lights, at least 3 lights and perhaps 4. All together they were in the shape of a perfect triangle, with the point toward us consisting of perhaps 2 lights close together. The lights were colored yellowish. The UFO was approximately due west from us, elevated approx. 40 degrees up from the horizon. My best guess is that its altitude was perhaps 3500-5000 feet above ground, and maybe 4 miles from our position."It" seemed to appear to be moving very very slowly to the east, almost as if in a slow moving hover. No sound could be discerned from it. We could see only lights. My wife took some pics with her cell phone but they just show a faint blur (pixelated) area. After about 5 minutes of looking, we went back to our apartment to get my monocular, binoculars, camera, and to make a quick report on Facebook, in the hopes that others saw it too. That took about 3-4 minutes, then we went back outside to the place we had observed the UFO. We could not locate the UFO again and noted that the sky appeared to be hazy now and clouding up some.((NUFORC Note: Witness elects to remain totally anonymous; provides no contact information. PD))