I do not know how “sparkle” works just what was said about it by the thread’s author. I would think of it like a retinal scan which is rather a wonder to understand because those work with you eye just inches away. So something at 15,000 feet (a random number, any significant height works) would mean some really good imaging equipment!
BBTs can go “invisible” using some kind of technology that keeps light from directly bouncing off it like a normal object. The one I saw went “shimmery” like heat waves off of the road ahead of you, then, just like that, I had a basic unobstructed view behind it! I only knew it was there because they left the “lights on” at the triangle’s apexes. A blur of light sounds about right.
Fast is an understatement! This was slowed down just so I could view it (I assume that because it kept circling over my head). It was doing some 80 – 100 miles in 6 seconds, fly north (or south, depending on where it was on the lap) for a couple, then move from the mountain range to the east of town, over my head, to out over the inlet all in 6 or 7 seconds, then do another lap. If it wanted to move out who knows how fast it could go. To me, it looked like it had its emergency brake on!
I tried to take a photo but all I got was a point of light. Same with my buddy on the other side of town!
After that, I’ve been “sparkled” several times. I’ve only seen a triangle once after that. It was really way up there. It looked like it chased off another light (craft?) at that height. I am assuming that we have a patrol of our airspace and do not like unwelcomed visitors. And a secret space fleet of BBTs.
How one works is pure speculation until the day one floats out of a hangar and the internet melts down, this site twice!