From: Canopus56 <canopus56@yahoo.com>

For a Class IIIA, that's probably too far. 3.5 kilometers is FAA tested "no effect" limit

Too far for what? Ann's laser was easily the brightest light in the valley, seen from my location, when I was on the beam axis. Maybe "no effect" means something other than "no visibility" in this instance? No time to check references this morning, sorry. I'll impose on you to educate me here.

Chuck, not to put a damper on your activities and enthusiam - which I respect immensely - but since you live in a landing corridor and are projecting across the 5-7 kilometer FAA "laser free" zone around SLC Int'l Airport, technically, what you are doing might violate FAA flight orders.

No worries, you didn't put a damper on anything. Being on the digest, I didn't even see your post until Sunday morning at 11:30. And even then, I respect your proclivity for thoroughness and attention to detail, and would worry if you hadn't found a regulation relating to this! ;) But I'm not worried about a visit from Men In Black. I first did this in about 1975, with a much more powerful laser and my parent's assistance, so I was fairly sure of the outcome. This time it was green instead of red, however, and the laser was much, much smaller! There were probably no FAA laser regulations at all back then. And my line-of-sight was very, very similar. This time, I was just west of Redwood road, well east of the runway axis, probably near the southern limit of the 5-7km zone, aiming no higher than 3-5 degrees and in a northeasterly direction- there was no chance of my beam being seen -at all- by any aircraft on-approach to SL Int'l. Ann was probably near the eastern limit of the zone, and projecting toward my location at the southern extreme- and she was aiming at an angle below the horizon- so I doubt that any aircraft at all could have seen either beam, with the exception of perhaps a Lifeflight, TV news, or constabulatory helicopter, which we were on the lookout for. I suppose if an aircraft were low enough to clip the trees or a cell tower, the pilot might have seen a green flash, but he'd have other worries. I don't mean to minimize FAA regulations, but we took reasonable precautions, chose our line-of sight carefully, and are very aware of the concerns of aviation regulatory agencies. This wasn't a "lets go out and flash our lasers around" kind of thing, or a high-powered commercial light show.

P.S. - I live in the Avenues, so I'll stick a pair of binos on Ensign around 8:00PM.

I doubt you saw anything. While the beams don't diverge that much, after seven to nine miles it's still wide enough to not be noticed on a dark, irregular background such as a hillside- the "dot" is probably fifty or sixty feet across by then. You'd have to be on-axis to see it. Next time, lets talk in advance and if you have line-of-sight to my location, I can target you, too. And just to play it by the numbers, I'll shift my site eastward to stay well clear of SL Int'l...and airport #2. Point-of-the-mountain might work well. I do need to work on my hardware, though, to make it easier to both collimate the laser with the telescope, and aim the telescope more precisely. Tripod pan/tilt heads are not a good enough choice, and neither are manual Dob mounts. An equatorial with slow-mo controls would be ideal. __________________________________ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.com