And despite reports to the contrary, Dave and wife Carol didn’t crack open a bottle of bubbly to celebrate a ‘champagne’ supernova. He said:

That was a bit of a fabrication. We had a little tipple but there is a Star party at Birr in Offaly on Saturday where the observatory is and I expect there will be a celebration then.

I searched through 2,611 galaxies looking for this.

I had a lot of false starts – it could have been an asteroid in the wrong place at the wrong time and I had to check to make sure it wasn’t a flaw on the camera. I double, triple, quadruple checked it before sending the photograph to colleagues in the UK to double check it. Then it was a case of filing the report and getting Professor Smart to confirm it. You can’t get too excited until you know for sure because a false report will sully your reputation.

Grennan works as a software developer for CIE which means he can’t stay up too late on weeknights to look at the stars. He built a shed, complete with sliding roof, in the back yard of his terraced house to house his equipment. His wife Carol is “very supportive”, he says:

She is very understanding. She loves to come out with a cup of tea and ask me, ‘How are things going tonight?’. Sometimes she helps me out with little things. She’s quite good but the most important thing she does is give me space to do what I do. Without an understanding wife, you’d be getting the whole, ‘Come in out of the cold, there’s hoovering to be done!’

His interest in astronomy was cultivated from childhood by another supportive woman, his mother.

From the age of about five, six, seven I would sneak out into the garden to look up at the stars and my late mum would come out and bring me a coat and put a hat on me. In 2008, when I was lucky enough to see an asteroid, I named it Catherine Griffin after her.

His only worry now is that his neighbour will still be talking to him after photographs of his back-yard observatory in today’s Irish Independent and Irish Times included her washing line in the background. He laughed:

I’m dreading talking to my neighbour. She had a famous washing line for the day. I didn’t see them out last night otherwise I would have warned her to bring in her clothes before the photographer came!

David Moore of Astronomy Ireland said that Grennan’s discovery was “the biggest thing ever discovered in Irish astronomy”. Speaking to TheJournal.ie this morning he added that Dave is probably Ireland’s top amateur astronomer and that the supernova – the death explosion of a massive star – he discovered lies on the outer edge of the universe, 300 million light years away. He explained:

We live in a galaxy which is like a city of stars, if you will. You only see a star explode once every 100 years so you have to look out into other galaxies to see them exploding there. There are dozens of supernovas discovered every year but these are by professional astronomers in huge observatories in places with clear skies. I knew about Dave’s potential discovery two weeks ago and I had been pestering him regularly for an update. It had to go through the official channels but it is wonderful.