1. Wow!
A potential alien signal
1977

2. Big Ear Ohio State University Radio Telescope, transit instrument
(Design similar to Nancay Radio Telescope)

3. Location on Sky
Sweeps across any given part of the sky in 72 sec

4. 21 cm Hydrogen line

5. What does the signal mean?

6. Many follow-ups, including:
Oak Ridge Observatory, 1987, 1989
12m NRAO West Bank, 1995
VLA, 1995, 1996
Mt. Pleasant Radio Obsy, 1999

7. Conclusion No clue! Could be Probably not…
Alien
Military
Noise (low chance but not impossible)
Probably not…
Accidental human (21cm banned)
Natural astronomical (narrow band)
2012 Aricebo beamed 10,000 Tweets to that direction of sky