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2026: The Year Ahead

Posted in Biographical, Euclid, Maynooth with tags , , , on January 1, 2026 by telescoper 
For last year’s words belong to last year’s language
And next year’s words await another voice.
And to make an end is to make a beginning.

From Four Quartets, ‘Little Gidding’ by T. S. Eliot.

So it’s New Year’s Day. Athbhliain faoi mhaise dhaoibh!

For me this brings the festive season to an end. I’ve been eating and drinking too much for the last week as one is supposed to. Last night I brought in the new year with a dish of roast duck and the last of the Christmas vegetables. I think I’ll be buying any sprouts and parsnips for a while. When the iron tongue of midnight told twelve, I had a glass of excellent Irish Whiskey in the form of Clonakilty Single Pot Still (46%). It has been a most enjoyable week, but heightened level of self-indulgence has been rather exhausting, and I’ll be taking things a bit easier for a few days before I go back to work on Monday. It’s hard work being a glutton.

Anyway, I thought I’d mention a few things looking forward to the New Year.

January will, as usual, be dominated by examinations, and especially the marking thereof. The first examination for which I am responsible is on January 12th. The examination, incidentally, will be held in the Glenroyal Hotel in Maynooth as the Sports Hall on campus – usually a major exam venue – is out of commission due to building work.

I have a couple of writing deadlines, in addition to having to correct the examinations, so it will be a busy January.

Then February sees the start of a new semester. I’ll be teaching Particle Physics again. I was a bit surprised to be asked to teach this again, as I was filling last year in for our resident particle physicist who was on sabbatical. I’m glad to be able to continue with it given the work I put in to do it last time. My other module is Computational Physics which I have taught at Maynooth every year since 2018, apart from 2024 when I was on sabbatical. This time, however, I will have to think hard about how to deal with the use of generative AI in the coursework.

Will I get to teach any astrophysics or cosmology at Maynooth before I retire? That’s looking very unlikely. I think it’s probable that the new academic year, starting in September, will find me teaching the same modules as last year.

The year ahead will also see the first data release (DR1) from the European Space Agency’s Euclid Mission. The date for that will be October 21st 2026. This is a hard deadline. There’s a huge amount of work going on within the Euclid Consortium to extract as much science as possible from the observations so far before the data becomes public, but you’ll have to wait until October to find out more!

This reminds me that I forgot to share this nice image from Euclid that was released just before Christmas.

Galaxy NGC 646 looking like a cosmic holiday garland in this image from the European Space Agency’s Euclid space telescope.

Once upon a time, WordPress used to send an email about the year’s blog statistics, etc, but it stopped doing that some time ago. I checked this morning, however, and learned that traffice on the blog in 2025 was up by 2.6% since 2024. I’m not sure how meaningful this is, because there is so much scraping going on these days. That figure doesn’t include the people who get posts via email or RSS or via other platforms such as the Fediverse.

While I’m on about social media I’ll mention a stat about my Bluesky account. I joined Bluesky in 2023 when I abandoned Xitter. As of today I have 8,078 BlueSky followers, which is more than I ever had on X, and with far higher levels of engagement and much friendlier interactions.

I’m also on Mastodon, although with a much smaller following (1.4k). This blog also has a separate existence on Mastodon here. I very much like the federated structure of Mastodon (which, incidentally, accords with my view of how academic publishing should be configured) and am a bit disappointed that it doesn’t seem to have caught on as much as it should.

That disappointment pales into insignificance, however, with the outrage I feel that my employer – along with most other universities – persists in using Xitter. Touting for trade in a far-right propaganda channel is no way for a institution of higher education to behave. You can read my views on this matter here.

And finally there’s the Open Journal of Astrophysics. The year ahead will see the 10th anniversary of our first ever publication – on an experimental prototype platform, long before we moved to Scholastica. It will be next Monday before we resume publishing, starting Volume 9. Which author(s) will be the first to get their final versions on arXiv in 2026? Stay tuned to find out!

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R.I.P. Yannick Mellier (1958-2025)

Posted in Euclid, R.I.P., The Universe and Stuff with tags , , , , on December 21, 2025 by telescoper

Last night I received a message via the Euclid Consortium conveying the very sad news of the death, at the age of 67, of the French astrophysicist and cosmologist Yannick Mellier (pictured left). Among many other things, Yannick was the Euclid Consortium Lead in which role he took on enormous responsibility for getting the project started and, with his team, keeping everything running. His loss is incalculable.

Yannick’s research work focussed on cosmology and the search for dark matter using gravitational lensing. Back in 1987 he was part of the observational team that discovered the first giant arc produced by strong gravitational lensing. He also did pioneering work in the field of weaking gravitational lensing with the Canada-France Hawaii Telescope in that regard starting back in 2000.

For well over a decade now Yannick had been involved with the European Space Agency’s Euclid mission. He was a major force right from the beginning, making the proposal, and after it was accepted leading the Consortium assembled to bring the project into being, preparing for launch, and dealing with the first data. The Euclid Consortium is a huge collaboration and it is impossible to overestimate the scale of the task facing the Lead. The first full data release (DR1) from Euclid will take place towards the end of next year (2026). It is sad beyong words that he did not live to see this.

During the period when I was Chair of the Euclid Consortium Diversity Committee I had a number of interactions with Yannick, sometimes dealing with difficult and confidential matters. I found him to be a man of great wisdom and sensitivity. Despite having many other things to deal with, including a long-term illness, he was unfailingly supportive and his advice was always sound.

The following is an excerpt from the message sent out yesterday:

Yannick’s death leaves a huge void within the consortium and our community. Those of us who have been here the longest know how hard he worked to make the Euclid project a success. He became its embodiment, working tirelessly to ensure its success; we owe him an immense debt of gratitude, and we will surely have the opportunity to reflect in detail on all that we owe him.

Indeed. I hope the Euclid Consortium – and the international cosmological community generally – will, at some stage, organize an appropriate tribute to Yannick.

Rest in Peace, Yannick Mellier (1958-2025)

Ar dheis Dé go raibh a anam

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Euclid’s “Tuning Fork”

Posted in Euclid, The Universe and Stuff with tags , , , on November 7, 2025 by telescoper

By way of a quick follow-up to yesterday’s post, here’s another Euclid Q1 product. This one is an updated version of the famous “Tuning Fork” representation of galaxy morphology:

Credits: Diagram: ESA/Euclid/Euclid Consortium/NASA, Diagram by J.-C. Cuillandre, L. Quilley, F. Marleau. Images alone: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre, E. Bertin, G. Anselmi

You can click on the image to make it (much) bigger.

A galaxy’s structure is a sign of its formation history and the environment in which it resides. Since early on, astronomers have ordered galaxies according to their visible structure – as a basis to understanding the underlying physics: This panorama of galaxies’ structure shows the ‘classical’ morphological sequence from ellipticals (E, left) to lenticulars (S0) through spirals (S) to irregulars and dwarfs (right). The fork divides barred and unbarred spiral families: originally only SA (unbarred) and SB (barred) galaxies were arranged in a ‘tuning fork’ layout, the addition of SAB (weakly barred) galaxies as a third branch is making this term increasingly challenging to use. Lowercase letters a to d indicate progressively later spiral stages (tighter to looser arms), the trailing m (e.g., SAm) denotes Magellanic, very-late-type systems (patchy, often one-armed). The Milky Way is classified as an SBc galaxy.

Below the main sequence there are three auxiliary panels showing objects not represented in the fork: (1) spiral galaxies seen edge-on, with varying bulge-to-disk ratios and warps; (2) interacting and merging galaxies illustrating gravitationally driven morphological change; and (3) the morphological diversity of dwarf galaxies.

You can read more about this image and the other Q1 results here. You can also find an interactive version of the plot here.

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Euclid and the Dark Cloud

Posted in Art, Euclid, The Universe and Stuff with tags , , , , on November 6, 2025 by telescoper

I haven’t posted anything recently about the European Space Agency’s Euclid mission, but I can remedy that by passing on a new image with text from the accompanying press release. This is actually just one of a batch of new science results emerging from the first `Quick Release’ (Q1) data; I blogged about the first set of Q1 results here.

Incidentally, I find the picture is very reminiscent of a famous painting by James McNeill Whistler.

Image description: The focus of the image is a portion of LDN 1641, an interstellar nebula in the constellation of Orion. In this view, a deep-black background is sprinkled with a multitude of dots (stars) of different sizes and shades of bright white. Across the sea of stars, a web of fuzzy tendrils and ribbons in varying shades of orange and brown rises from the bottom of the image towards the top-right like thin coils of smoke.

Technical details: The colour image was created from NISP observations in the Y-, J- and H-bands, rendered blue, green and red, respectively.  The size of the image is 11 232 x 12 576 pixels. The jagged boundary is due to the gaps in the array of NISP’s sixteen detectors, and the way the observations were taken with small spatial offsets and rotations to create the whole image. This is a common effect in astronomical wide-field images.

Accompanying Press Release

The above view of interstellar gas and dust was captured by the European Space Agency’s Euclid space telescope. The nebula is part of a so-called dark cloud, named LDN 1641. It sits at about 1300 light-years from Earth, within a sprawling complex of dusty gas clouds where stars are being formed, in the constellation of Orion.  

This is because dust grains block visible light from stars behind them very efficiently but are much less effective at dimming near-infrared light.  

The nebula is teeming with very young stars. Some of the objects embedded in the dusty surroundings spew out material – a sign of stars being formed. The outflows appear as magenta-coloured spots and coils when zooming into the image.  

In the upper left, obstruction by dust diminishes and the view opens toward the more distant Universe with many galaxies lurking beyond the stars of our own galaxy. 

Euclid observed this region of the sky in September 2023 to fine-tune its pointing ability. For the guiding tests, the operations team required a field of view where only a few stars would be detectable in visible light; this portion of LDN 1641 proved to be the most suitable area of the sky accessible to Euclid at the time. 

The tests were successful and helped ensure that Euclid could point reliably and very precisely in the desired direction. This ability is key to delivering extremely sharp astronomical images of large patches of sky, at a fast pace. The data for this image, which is about 0.64 square degrees in size – or more than three times the area of the full Moon on the sky – were collected in just under five hours of observations. 

Euclid is surveying the sky to create the most extensive 3D map of the extragalactic Universe ever made. Its main objective is to enable scientists to pin down the mysterious nature of dark matter and dark energy. 

Yet the mission will also deliver a trove of observations of interesting regions in our galaxy, like this one, as well as countless detailed images of other galaxies, offering new avenues of investigation in many different fields of astronomy. 

In visible light this region of the sky appears mostly dark, with few stars dotting what seems to be a primarily empty background. But, by imaging the cloud with the infrared eyes of its NISP instrument, Euclid reveals a multitude of stars shining through a tapestry of dust and gas. 

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Euclid Flagship 2 Update

Posted in Euclid, The Universe and Stuff with tags , , , on September 22, 2025 by telescoper

I was thinking earlier today that it’s been a while since I last posted anything about the European Space Agency’s Euclid Mission but I’ve got an excuse to remedy that today because there is a brand new a press release about the Euclid Consortium’s Flagship 2 simulations, a (low-resolution) visual representation of one of which is shown above.

The news is that the largest ever synthetic galaxy catalogue is now public; a team of 8 institutions within the Euclid Consortium, led by the Institute of Space Sciences (ICE-CSIC) and the Port d’Informació Científica (PIC) in Barcelona have developed this `mock’ catalogue, which includes 3.4 billion galaxies, each with 400 modelled properties available for the scientific community. It was constructed to help analyse data from the Euclid mission, but has many other potential uses so is being shared otuside the Consortium.

You can read more about this catalogue, and also find out how the access the simulated catalogues, here. You could also read the scientific paper describing the flagship simulations here.

P.S. The first main data release from Euclid (known to its friends as DR1) will take please on October 21, 2026. That’s just 13 months away…

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Wednesday at #EAS2025

Posted in Biographical, Euclid, The Universe and Stuff with tags , , , , on June 25, 2025 by telescoper

I spent most of today at the EAS 2025 sessions about Euclid. These were mainly about the Q1 data release I blogged about here, although there were some talks about what to expect about the first full data release (DR1), which is due towards the end of next year (2026), before I retire.

There were three Euclid sessions, one in the morning and two in the afternoon; I’m writing this during the last of these.

I was reminded this morning that the word “plenary” is derived from the Latin plenus, meaning “full”. This explains why there are no free seats for the plenary session, so I had to watch the stream in one of the overflow theatres.

I also attended a lunchtime session about the Square Kilometre Array Observatory (SKAO). This was interesting, though the first full data release from SKAO will not happen until after I’ve retired.

And, to end the day, I’m at a reception and meeting of SKA Ireland, a group campaigning for Ireland to join the SKAO.. There’s win.

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Last Remarks

Posted in Biographical, Education, Euclid, Maynooth, The Universe and Stuff, Uncategorized with tags , , on May 11, 2025 by telescoper

On Friday (9th May), the last day of undergraduate teaching at Maynooth, I gave the last lecture in my module on Particle Physics. I actually finished the syllabus on Tuesday (6th) so the final one was more a revision class than a lecture. I used it to go through some past examination questions and (try to) answer some general points raised by the class.

What surprised me about this lecture was that, as has usually been the case, there was more-or-less a full attendance. Examinations in Maynooth start on Friday (May 16th), but the Particle Physics examination is not until May 27th, near the end of the examination period. I therefore expected that many students would be concentrating on their revision for their other modules, which have exams earlier in the season or finishing their projects (which are due in before the exams start). There were one or two absences, but most came anyway. In fact there was even an extra student, one of our MSc students. When I saw him at the back of the lecture hall I asked, jokingly, why he had come. He replied “I haven’t got anything better to do”. I wasn’t sure how to interpret that!

That lecture was at 11am. Later that day, at 3pm, I gave a Departmental colloquium (which had quite a big audience). The title was Euclid: The Story So Far and the abstract was

The European Space Agency’s Euclid satellite was launched on 1st July 2023 and, after instrument calibration and performance verification, the main cosmological survey is now well under way. In this talk I will explain the main science goals of Euclid, give a brief summary of progress so far, showcase some of the science results already obtained, and set out the time line for future developments, including the main data releases and cosmological analysis.

The audience for these talks is very mixed: experimental and theoretical physics staff, postgraduates and even some undergraduate students (including some who were in my lecture earlier) so it was quite a general talk rather than one I might give to an specialist astrophysics audience. If you’re interested you can find the slides here.

Having a quick cup of tea after the end of the talk and before I headed off to catch the train, I talked briefly with a student who is taking his final examinations at Maynooth this year. He told me that I had actually given the first lecture he attended when he had just started his first year and the colloquium was the last talk he would attend at Maynooth. That would be the case for quite a few students in the audience, I suppose, but it won’t be true for any in future: I am no longer teaching any modules taken by first year students, and I’ll be retired when the current first year students graduate…

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Euclid on Sky

Posted in Euclid, The Universe and Stuff with tags , , , on May 2, 2025 by telescoper

I haven’t posted much recently about the European Space Agency’s Euclid Mission but I’ve got an excuse to remedy that today as I’ve just seen that the Special Issue of Astronomy & Astrophysics called Euclid on Sky has at last been published (with a date of 30th April 2025). This contains the main mission and instrument overview papers as well as scientific papers relating to the Early Release Observations. All the individual papers have been on arXiv for some time already.

You can access the Special Issue here.

The main mission overview paper has 1139 authors (including yours truly); that’s definitely the longest author list I’ve ever been on! The arXiv version has been available for almost a year and has already got 254 citations. Here is the abstract:

The current standard model of cosmology successfully describes a variety of measurements, but the nature of its main ingredients, dark matter and dark energy, remains unknown. Euclid is a medium-class mission in the Cosmic Vision 2015-2025 programme of the European Space Agency (ESA) that will provide high-resolution optical imaging, as well as near-infrared imaging and spectroscopy, over about 14,000 deg^2 of extragalactic sky. In addition to accurate weak lensing and clustering measurements that probe structure formation over half of the age of the Universe, its primary probes for cosmology, these exquisite data will enable a wide range of science. This paper provides a high-level overview of the mission, summarising the survey characteristics, the various data-processing steps, and data products. We also highlight the main science objectives and expected performance.

Here’s Figure 1.

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The Spanish Power Outage

Posted in Barcelona, Biographical, Euclid with tags , , on April 28, 2025 by telescoper

The first I knew about today’s massive failure of electricy grids across the Iberian peninsula was at 4 o’clock this afternoon, when I tuned in to a regular Euclid telecon and found that the expected speaker wasn’t able to give their presentation because there was no power in Spain. I was subsequently shocked to discover the scale of the outage, the cause of which remains unknown (at least to me). I’ve often thought that Ireland’s power grid was a bit unstable but I’ve never known the whole country to be shut down!

It all reminded me of the 2003 power blackout in the North-Eastern USA and Canada.

There has been speculation about an “unusual atmospheric phenomenon” being the cause, but that seems somewhat implausible. Indeed, nothing I’ve read so far about the cause of this event makes much sense.

This time last year I was in Barcelona, and today’s events got me thinking what it would have been like to be there without any power. The apartment I was living in was all-electric so there would have been little I could do – no light, no cooking, no air conditioning, no internet, no TV, no radio. I was on the top floor and the lift was powered by electricity so I would have had to use the stairs to get in or out. It would have been an interesting experience to see the city in total darkness from my balcony.

Had I been in the Department of Physics when the power went off I probably would have had to walk home, as the Metro would not have been running and with all the traffic lights off the roads would be even more chaotic than usual. That would have meant a walk of an hour or so, which would have been annoying, but feasible. Come to think of it, people actually on the Metro when the failure happened would have been stuck in a tunnel which must have been very unpleasant.

Anyway I hope all my friends and colleagues in Spain are not too badly inconvenienced and that this very weird event doesn’t lead to any serious issues. I understand the power supply to hospitals is secure, which is a relief. I must admit though I am very curious to learn the cause of this catastrophic failure. Was it human error? Deliberate sabotage? Or was it really an “unusual atmospheric phenomenon”? No doubt there will be a full investigation and we’ll find out in due course.

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Crisis at NASA

Posted in Euclid, Politics, The Universe and Stuff with tags , , , on April 23, 2025 by telescoper

The scientific community has been waiting for several weeks to find out precisely how heavily the Trump/Musk axe would fall on the National Aeronautics and Space Administration (NASA); this article reveals the shocking scale of the proposed cuts.

Under the proposal, NASA’s Science Mission Directorate (SMD) would receive almost a 50% reduction in its Budget. Within the individual SMD Divisions:

  • Planetary Science would have its budget cut from the current level of $2,717 Million to $1,929 Million;
  • Earth Science would see a cut from the current budget level of $2,195 Million to $1,033 Million;
  • Astrophysics would decrease from its current level of $1,530 Million to $487 Million;
  • Heliophysics budget would decrease from its current level of $805 M to $455 M.

It’s very bad news all round for NASA science, but the worst hit is Astrophysics (which includes cosmology) where the proposed cut is about two-thirds, which would be truly devastating. According to the American Astronomical Society,

The proposed cut to the astrophysics budget is likely to result in the cancellation of the Nancy Grace Roman Space Telescope, a Great Observatory that would revolutionize our understanding of dark matter and dark energy while also detecting hundreds of thousands of planets in other solar systems. As the Roman Space Telescope is already fully assembled and on budget for a launch in two years, a cancellation of the mission would be a significant waste of taxpayer dollars. 

The Nancy Grace Roman Space Telescope (formerly known as WFIRST) is in many ways complementary to Euclid, though it will survey a smaller area of sky it has an telescope twice the diameter of Euclid so will reach fainter magnitudes. It has been threatened before, in Trump’s previous administration, but it survived. It is not clear that it will do so again as the current composition of Congress is not weighted favourably.

Those of us outside the United States can do little, but in case anyone reading this is in America the AAS has an Action Alert for you to contact your representative(s) to vote against the proposal.

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