David Grennan, 39, was just about to go to bed on September 17 when he spotted the exploding star through the telescope at his home observatory in Raheny in Dublin.
He beat professional astronomers across the globe with his discovery, which was officially confirmed by international astronomy authorities earlier this week.
It is the first supernova to be discovered in Ireland.
Mr Grennan explained: ‘I was going to wrap things up and go to bed and then I thought, “Dave, you don’t make discoveries in bed – at least not these sort of discoveries”.’
WHAT IS A SUPERNOVA?
The explosion happened long before dinosaurs roamed the Earth.
Mr Grennan discovered the supernova by comparing images taken of the same area in the sky in August and September.
He noticed a black spot in the later images that had not been there previously. Although it appears tiny on the page, he said the force of the supernova would be equivalent to 100million Earths exploding at the same time.
Mr Grennan works as a software developer for CIÉ but spends all his spare time star-gazing.
‘It was a hobby I developed when I was five years old,’ he said. ‘I was always wondering about the stars and the atmosphere.
‘I used to stand out in my back garden every night and my mother would come out but instead of telling me to come inside, she would put a coat and scarf on me and let me stay out, and call me back in when it got too late.’
There’s nothing particularly sophisticated about the observatory – he said he bought most of the equipment in a DIY store and made it single-handedly over a couple of months.
It includes a retractable roof so he can keep out of the rain.
‘Unfortunately, the Irish weather doesn’t afford me much time to observe the skies but I try to devote about two nights a week to it.’
‘I couldn’t really do it without my wife Carol,’ he added, ‘because she helps me look at the images and spot anything interesting.
‘Naturally I’m very excited at having made this discovery, especially since it’s a first for Ireland. I find myself wondering if there were some poor souls living on planets surrounding the star when it exploded. one thing is for sure: we’ll never know.’
He added: ‘I would really love to see younger kids getting interested in science and astrophysics because it’s amazing what you discover.
‘I firmly believe that science is a key to the way out of our economic difficulties, which will drive the knowledge based economy they are trying to promote.’
Two years ago, Mr Grennan discovered an asteroid just three metres wide and named it after his mother Catherine Griffin, who had encouraged his interest in the stars when he was a boy. The supernova is expected to remain visible with a telescope for about two or three months before it fades.