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Monday 2 October 2023 Dublin: 13°C
Julien Behal/PA Archive/Press Association Images Dave and his wife Carol in their back garden observatory
# Astronomy
"I nearly fell off my chair": Dublin man makes second supernova discovery
Amateur astronomer Dave Grennan has been called Ireland’s ‘premier supernova hunter’ after discovering two supernovae in just two years.

RAHENY MAN DAVE Grennan made headlines when he discovered his first supernova back in 2010 from his back-garden observatory – and just two years later, he has discovered his second.

The discovery of celestial explosion 2012ej (it was given its formal designation by the International Astronomical Union yesterday) is a huge one, not least for Grennan himself.

This latest supernova is a star that exploded 123 million years ago in a galaxy in the constellation Lynx, and amateur astronomer and Astronomy Ireland member Grennan found it after years of searching.


“This is quite exciting,” a delighted Grennan told

I think I’m nearly more excited about this one than the last one! This one has been so long coming since the last one. It was such hard work to get there but eventually it all came together.

He described finding the supernova as “very fortuitous in many ways”, as he had taken photos of 117 different galaxies that night. The first 112 had nothing on them, and the following four had cloud covering them.

“The very last one was 117. I looked at it and I nearly fell off my chair. I went ‘Oh my god’. Sometimes you see things and you think maybe… but this was so obvious and so clear. I knew straightaway this was a supernova – but it might have been one that was already discovered.

Image via

Grennan then examined all the relevant records and to his relief found no trace of the supernova being discovered before:

I’ve been at that point a couple of times and only discovered at the last hurdle it had been discovered a week ago by a big professional survey in the States, so I tend not to get too excited until I’ve ticked all the boxes.

He submitted the information and got the official confirmation from the International Astronomical Union yesterday, while he was in work.

“You only get to name objects that will be permanently in the sky,” said Grennan of its name, 2012ej, explaining that while comets and asteroids can be named, exploding stars are not permanent.

Years of work

His discovery “didn’t happen by accident – it was the culmination of years of work, investing in equipment and processes and procedures”, he said.

It’s not just down to one person. There are a lot of people out there in the professional astronomy community who are more than willing to help out someone like myself and offer advice and tips

The other important person is his wife, Carol, who he describes as “wonderful”.

Without a partner like Carol you just couldn’t devote the number of hours that you’ve got to devote to doing this.

On a typical evening, if the sky is clear – which, being Ireland, it isn’t always – Grennan could be working in the shed for hours. In fact, his most recent discovery came at 2.30am, and the first thing he did was wake Carol up to tell her the good news.

She’s good to put up with it – she loves it herself. She’s my first clearing house. Anytime I have something that I look at that I think might have something on it, I show it to her – maybe even at strange hours when she’s asleep.

Since he became the first person in Ireland to discover a supernova in 2010, Grennan has been examining thousands and thousands of galaxies. “There are nights where you search thousands and go to bed with nothing to show for it,” he said.

Knowing that there are people out there “that have multi-million-dollar telescopes up mountains in Arizona and [it] is their day job” can sometimes make searching feel like a very tough job. But discoveries like this latest one make it all worth it.

As an IT analyst, he has used his skills to write a lot of the software he uses to find the supernovae, which is a huge advantage.

If there is something I don’t like about the software, I can go re-programme it.

As well as looking for supernovae, Grennan also tracks asteroids, to make sure they aren’t straying in Earth’s direction. Though some have come closer to us than the moon is, so far there has been nothing that caused major worry, though he admits:

When you see these [asteroids] whizzing by, you are thankful that it did go by and it didn’t come any closer.


Last time he discovered a supernova, Grennan celebrated with a cup of tea.

“The tea was definitely out again,” he said of this occasion. “But the champagne might be coming out this time”.

No doubt the champagne will indeed be flowing when he attends the Astronomy Ireland ‘star-B-Q” in September, where he will be giving a talk on his work.


David Moore, editor of Astronomy Ireland magazine, told that this is the second supernova to have been discovered from Ireland and “required lots of patience and some of the most sophisticated equipment in Irish hands”.

A supernova is the biggest explosion in the universe, after the Big Bang. It would be like billions of Earth’s exploding all at once in an unimaginably violent event that would wipe out all life on our planet if it happened to any of the stars near our Sun. To discover such an event – not to mention two! – from Irish soil is a truly remarkable feat

Moore said that Grennan “does an awful lot of hard work every clear night and has set himself as Ireland’s premiere supernova hunter”.

Read: ‘Champagne’ supernova spotter celebrates with a nice cup of tea>

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