Walking home tonight from dinner with a friend in the East Village, NY, I was passing south along Pitt Street, one block north of Delancey, when I heard the throaty rumble of a low-flying plane getting louder overhead. I didn’t pay it much attention but it was loud enough for me to clock it. Up ahead, I saw three guys emerge from one of the projects on the east side of Pitt St. As I got closer to them, they paused. The plane was passing right above us, heading north along the east river Manhattan shoreline, and I suddenly saw what could only be described as a wide, flat green laser beam start sweeping the street from the plane. It passed over the three guys up ahead, and then me. It was like a giant laser bar-code scanner passing across every contour of the street - for a brief second like suddenly being in a bad light show at a 1990s rave. The three guys ahead of me stopped in their tracks, dumbfounded. I caught up with them and we all looked at each other, then back up to the sky, and then saw this fat triangle of green light beaming down from the plane as it headed north. I talked to them, and none of us could work out what it was, but we had all seen the same thing. I continued walking south towards Grand Street, where I live, and just as I was entering my building I heard the plane come back, this time flying south. I stopped and watched it’s green beam cover ground just a little further west of where I’d been walking. As I write this I can still hear the plane making passes overhead - it’s engines have quite a distinct sound.
As related by a friend, November 19th, 2012. This appears to be LIDAR scanning of New York in operation. This was first proposed in 2010, and reported by Fast Company and the New York Times. Green LIDAR in particular is used for marine environments - it seems likely that the current scan is in response to recent flooding caused by Hurricane Sandy. The technical term for this process is EEARL, but I haven’t yet been able to establish who is doing the scanning.