Ian Curtis' death: what was the tribute song?

[Steve]

Hi, I have a question I hope you can solve. I have a blog dedicated to 
the Festive 50 called 'Teenage Kicks' 
(http://festivefifty.blogspot.com) and I recently did a post about Joy 
Division. On at least two websites, it stated that John 
played 'Atmosphere' on his Monday May 19 1980 show as a tribute to Ian 
who had died the day before. However, two other blog members say it 
was 'New Dawn Fades' that was played. Can any body shed any light, 
indeed does anybody have a recording of that show? I would love to 
know. Cheers!