Like all UFOs, I don't suppose you got a good photo!
Maybe a Robin ATL L as in the article below? Doubtful, as it looks
British, but I can't help thinking it approriate with "ATL" in the name

I don't think you would have mistaken it for several of the others
listed in the article
http://www.answers.com/topic/v-tail
Scott
Kyle Boatright wrote:
Don't think so. Don't forget the "skinny" aft fuselage I described. It was
wasp waisted, like the current Diamonds or maybe a Lancair.
For what it is worth, I don't think it was a Moni either.
KB
"Scott" wrote in message
news
Was this it??
http://www.sonexaircraft.com/aircraft/xenos.html
Scott
Scott wrote:
UFO??? 
Did (or does) Sonex make a V-tail motorglider?
Scott
Kyle Boatright wrote:
Yesterday, we departed Falcon Field, South of Atlanta (also the home of
Aircraft Spruce East) and noticed traffic at about 10 O'clock high. At
first, I thought it was one of the Diamond Eclipse trainers that
routinely fly out of Falcon. Low wings with a high aspect ratio, skinny
aft fuselage, trigear... As we got closer, it was obvious that it
wasn't an Eclipse..
Why? Well, it was slower than the Diamonds, was relatively small, and
had a V-tail.
What was that thing?
--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)
--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)