Euclid Update – Revised Timeline

Posted in Euclid, mathematics, The Universe and Stuff with tags , , , , , , , , on June 16, 2026 by telescoper

In a post last week I hinted that I hoped soon to be able to provide an update on progress with the European Space Agency’s Euclid Mission. People within the Euclid Consortium have known for some time, but it has now been officially announced by ESA, that the timeline for the first full Data Release (DR1; originally scheduled for October 2026) has now been revised.

The plan now is for DR1 to happen in stages, with a first tranche to occur in November 2026 (precise date yet to be announced). The complete data release will take place in mid-2027 (probably in June). The sky area covered by DR1 will be about covering a large sky area of about 1900 deg².

To give a little more background, the data products from the Euclid survey are divided into three levels of data processing function:

  • LE1 – the “raw” data frames, prior to calibration, generated at the Science Operations Centre from the time-ordered data and telemetry received from the spacecraft
  • LE2 – the calibrated and corrected data for the two instruments (VIS and NISP) – images, spectra, catalogues of point sources, etc
  • LE3 – the high-level data products (galaxy catalogues, cosmic shear maps, etc) designed for cosmological analysis

The first release will comprise LE1 and LE2 only. This will be called DR-Foundation. The LE3 data will be added next year to make the full DR1. Since LE3 is required for the cosmological analysis that is the prime motivation for the Euclid mission, it follows that there will be no official cosmology results from Euclid DR1 until mid-2027 at the earliest. Other results based on “Foundation” data may of course emerge before then.

I hope this clarifies the situation.

P.S. Irish physicists and astronomers will be particularly interested to know that the LE1 data includes information about the spacecraft and instrument pointing orientations, which is stored in the form of quaternions

Bloomsday 2026

Posted in Literature with tags , , , , on June 16, 2026 by telescoper

So it’s 16th June, a very special day in Ireland – especially Dublin – because 16th June 1904 is the date on which the story takes place of Ulysses by James Joyce. Bloomsday – named after the character Leopold Bloom – is an annual celebration not only of all things Joycean but also of Ireland’s wider cultural and literary heritage.

If you haven’t read Ulysses yet then you definitely should. It’s one of the great works of modern literature. And don’t let people put you off by telling you that it’s a difficult read. It’s a long read,  that’s for sure -it’s over 900 pages – but the writing is full of colour and energy and it has a real sense of place. It’s a wonderful book. I’ve read it three times now, once as a teenager, once in my thirties, and again a few years ago when I’d reached sixty. Don’t worry if you don’t understand all of Ulysses. It’s like life: most of us never figure out what that’s all about, and it doesn’t really matter.

Joyce once said of Ulysses

I’ve put in so many enigmas and puzzles that it will keep the professors busy for centuries arguing over what I meant.

Well, he wasn’t wrong about that! They’re still arguing, The text is a kind of cultural celebration: references to Greeky mythology jostle with popular songs, lists, parodies, question-and-answer sections, and records of the characters innermost thoughts. The book is full of allusions and part of the fun is trying to follow them up. And anyone who likes puns will have a field day!

Anyway, here’s an excerpt. It’s from near the start of Chapter 4, where we meet Mr Leopold Bloom for the first time and discover that he’s fond of cats. He is making breakfast for his wife Molly, who is still in bed. I don’t know if Joyce ever had a cat, but he obviously knew a lot about them!

–o–

Another slice of bread and butter: three, four: right. She didn’t like her plate full. Right. He turned from the tray, lifted the kettle off the hob and set it sideways on the fire. It sat there, dull and squat, its spout stuck out. Cup of tea soon. Good. Mouth dry. The cat walked stiffly round a leg of the table with tail on high.

—Mkgnao!

—O, there you are, Mr Bloom said, turning from the fire.

The cat mewed in answer and stalked again stiffly round a leg of the table, mewing. Just how she stalks over my writingtable. Prr. Scratch my head. Prr.

Mr Bloom watched curiously, kindly the lithe black form. Clean to see: the gloss of her sleek hide, the white button under the butt of her tail, the green flashing eyes. He bent down to her, his hands on his knees.

—Milk for the pussens, he said.

—Mrkgnao! the cat cried.

They call them stupid. They understand what we say better than we understand them. She understands all she wants to. Vindictive too. Cruel. Her nature. Curious mice never squeal. Seem to like it. Wonder what I look like to her. Height of a tower? No, she can jump me.

—Afraid of the chickens she is, he said mockingly. Afraid of the chookchooks. I never saw such a stupid pussens as the pussens.

—Mrkrgnao! the cat said loudly.

She blinked up out of her avid shameclosing eyes, mewing plaintively and long, showing him her milkwhite teeth. He watched the dark eyeslits narrowing with greed till her eyes were green stones. Then he went to the dresser, took the jug Hanlon’s milkman had just filled for him, poured warmbubbled milk on a saucer and set it slowly on the floor.

—Gurrhr! she cried, running to lap.

He watched the bristles shining wirily in the weak light as she tipped three times and licked lightly. Wonder is it true if you clip them they can’t mouse after. Why? They shine in the dark, perhaps, the tips. Or kind of feelers in the dark, perhaps.

I’ll also mention that if you have about 30 hours to spare you can listen to all of a radio broadcast of Ulysses from 1982.

The Cambridge Whistleblowing Saga

Posted in Harassment Bullying etc with tags , , , , on June 15, 2026 by telescoper

This is an update concerning the Employment tribunal I mentioned a couple of weeks ago.

The claimant in the case is Professor Wyn Evans of the Institute of Astronomy at the University of Cambridge. Now that he has finished given evidence, it is now possible to release some of the background publicly. You can read a summary here. If you follow that link you will see reference to this guest post, published on this blog in late 2022:

That old post was carefully anonymised for legal reasons, but it can now be revealed that the Department concerned is, nor surprisingly given the affiliation of the claimant, the Intitute of Astronomy at the University of Cambridge.

I will refrain from commenting further as the case is ongoing, but you can follow updates here. There is also piece about the case in the Guardian here.

P.S. Yes, it has taken a very long time for the matter to reach a head.

My Bucket’s Got a Hole in It

Posted in Biographical, Jazz, Maynooth with tags , , , , on June 14, 2026 by telescoper

“Only connect” is EM Forster’s best known adage about writing, though he didn’t mean it in the context of a “shitty WordPress blog”. Nevertheless I do find it fun sometimes to connect disparate things, so here goes.

I was doing a turn in the garden this afternoon when I noticed that an old bucket left here by the previous occupant had corroded enough to develop a hole:

This reminded me of the old song My Bucket’s Got a Hole in It and especially this very enjoyable version of it by Humphrey Lyttelton’s 1954 seven-piece live at the Conway Hall in London.

It’s hard to believe that it’s 18 years since Humph passed away, but it’s great to hear his voice again in the introduction to the track which ends the A side of the album Humph at the Conway. The cartoon on the cover is by him too. The record features Humph on trumpet, the clarinet by Wally Fawkes (who plays the first clarinet solo) and Bruce Turner on alto sax who switches to clarinet for the second solo but plays sax in the ensembles which sound absolutely terrific as a result. Many “trad” jazz fans took against Humph for including a saxophonist in his band, but Bruce Turner was a great musician and added a new dimension. The other members of the band were Johnny Parker (piano), Micky Ashman (bass), Freddy Legon (banjo) and George Hopkinson (drums).

So that’s one connection. Another is that yesterday saw the announcement of the King’s Birthday Honours in the UK, which was not covered widely here in in Ireland, but which independently reminded me that Humphrey Lyttelton turned down a knighthood on principle back in 1995. Good for him!

For Retired Engineers…

Posted in Biographical, The Universe and Stuff with tags , , , , on June 14, 2026 by telescoper

Many moons ago, just before I moved from Cardiff for my stint at Sussex University, I decided to ditch all the unsolicited letters and manuscripts I’ve accumulated over the years about “alternative” theories of relativity, cosmology, and whatnot. I don’t know why I had kept so many of them for so long, but I no longer have most of them. I did keep one or two of the best ones, however. Here’s an example:

I could never make head nor tail of this, but sometimes had a vague feeling that it might just be a sort of cosmic Rosetta Stone, offering up the Secrets of the Universe in diverse languages. Sadly, however, it’s more likely that the languages involved are Balderdash, Gibberish and Gobbledegook. At the time I wrote:

I regret to announce, therefore, that the plethora of papers telling me why Einstein was wrong, how the Universe is really in the shape of a spiral, how the Great Pyramid of Giza explains the Higgs Boson, and why the Big Bang couldn’t have happened, will have to go to the Great Shredder in the Sky (if that’s where it is).

Anyway, to all my correspondents all I can say is that I’ve enjoyed reading your letters – you must be very fond of your old typewriters – and I’m grateful for the time you took to draw the diagrams by hand in so many lovely colours. And I’m impressed by your qualifications as Electrical Engineers. Really. I’m sorry I didn’t reply to you all individually, but I just didn’t have the time. And now it pains me to realise I don’t have the space either…

I still get such things, of course, but they always come by email nowadays and usually end up in the spam folder, where I do not disturb them. I never reply, of course. Life’s too short.

I know I’m not the only one to have noticed the fact that many – indeed most – such correspondents are Electrical Engineers (usually retired). I was delighted therefore to see that there’s now a nice little paper on arXiv by David Garfinkle with the title Relativity for Retired Engineers and the abstract:

We provide some guidance and examples to clear up common misconceptions about special relativity. These misconceptions often come from trying to express the truths of special relativity in Newtonian terms rather than in terms more natural to special relativity itself. This conceptual stance can also help in attaining a better understanding of general relativity.

Readers may consider referring their correspondents to this source…

Weekly Update from the Open Journal of Astrophysics 13/06/2026

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , , on June 13, 2026 by telescoper

It’s Saturday again so it’s time for another update of activity at the Open Journal of Astrophysics. Since the last update we have published a further three papers, bringing the number in Volume 9 (2026) to 122 and the total so far published by OJAp up to 570.

I will continue to include the posts made on our Mastodon account (on Fediscience); these announcements also show the DOI for each paper.

The first paper to report this week, published on Thursday 11th June, is “Dancing Streams In Merging Halos: Stellar Streams in a MW–LMC-like merger” by (all based in the USA): Sachi Weerasooriya (Carnegie Observatories), Tjitske Starkenburg (Northwestern U.), Emily C. Cunningham (Columbia U.) & Kathryn V. Johnston (Flatiron Institute). This article explores how galaxy mergers, like the Milky Way-Large Magellanic Cloud merger, significantly alter the properties and structures of stellar streams, challenging the recovery of their initial orbits. It is in the folder marked Astrophysics of Galaxies.

The overlay for this paper is here

You can find the officially accepted version on arXiv here and the announcement on Fediverse here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Dancing Streams In Merging Halos: Stellar Streams in a MW–LMC-like merger" by (all based in the USA): Sachi Weerasooriya (Carnegie Observatories), Tjitske Starkenburg (Northwestern U.), Emily C. Cunningham (Columbia U.) & Kathryn V. Johnston (Flatiron Institute).

doi.org/10.33232/001c.163211

June 11, 2026, 7:05 am 1 boosts 0 favorites

The second paper for this week, also published on Thursday 11th June but in the folder Cosmology and Nongalactic Astrophysics is “X-SORTER (X-ray Survey Of meRging clusTErs in Redmapper): X-ray and Spectroscopic Characterization of 12 Optically Selected Galaxy Cluster Merger Candidates” by Christopher Hopp, David Wittman, Rodrigo Stancioli, Zhuoran Gao & Faik Bouhrik (UC Davis) and Scott Adler (Rochester), all based in the USA. The X-SORTER program identifies merging galaxy clusters to study dark matter interactions, using optical indicators and X-ray observations. This method efficiently identifies active clusters suitable for detailed dark matter studies.

The overlay for this one looks like this:

The official version of the paper can be found on arXiv here and the Fediverse announcement here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "X-SORTER (X-ray Survey Of meRging clusTErs in Redmapper): X-ray and Spectroscopic Characterization of 12 Optically Selected Galaxy Cluster Merger Candidates" by Christopher Hopp, David Wittman, Rodrigo Stancioli, Zhuoran Gao & Faik Bouhrik (UC Davis) and Scott Adler (Rochester), all based in the USA.

doi.org/10.33232/001c.163212

June 11, 2026, 7:25 am 1 boosts 0 favorites

The third and final paper of the week, published on Friday 12the June in the folder Earth and Planetary Astrophysics, is “JCMT Constraints on the Early-Time HCN and CO Emission and HCN Temporal Evolution of 3I/ATLAS” by Jason T. Hinkle (U. Illinois, USA) and 6 others based in the USA and Chile. This article presents observations of the third Interstellar Object, 3I/ATLAS, providing early sub-mm constraints on its activity. The findings suggest a steeper production rate slope than typical Solar System comets.

The overlay for this one is here:

The final, accepted version can be found on arXiv here and the Mastodon announcement is here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "JCMT Constraints on the Early-Time HCN and CO Emission and HCN Temporal Evolution of 3I/ATLAS" by Jason T. Hinkle (U. Illinois, USA) and 6 others based in the USA and Chile.

doi.org/10.33232/001c.163250

June 12, 2026, 6:50 am 1 boosts 2 favorites

And that concludes this week’s update. It has been a slow week on the publishing front, but the main reason is that we have a big backlog of papers accepted but waiting for the authors to put their final versions on arXiv and we can’t do anything about that! I’ll do another update next Saturday.

R.I.P. David Hockney (1937-2026)

Posted in Art, LGBTQ+, R.I.P. with tags , , on June 12, 2026 by telescoper

Today brought sad news of the death of artist David Hockney at the age of 88. Hockney was one of the leaders in the pop art movement, which involved assimilating and distilling ideas from popular culture and his career spanned painting, drawing, photography, printmaking and stage design. The last exhibition I saw by him consisted of wonderful drawings done on an IPad. That was about 15 years ago; he remained remarkably active and productive well into old age.

Throughout his career, Hockney’s work was often inspired by his fascination with light, especially its interplay with water, as well as his unique sense of space and unusual use of colour. His most famous early expressions of these were realised in California, where he became obsessed with the bright sunshine and the plethora of swimming pools.

As Hockney’s fame grew his work became very collectible, commanding huge prices at auction, so much of it ended up in private collections. This large-scale work, A Bigger Splash, painted in 1967, followed a smaller painting, The Splash (1966). The earlier work fetched around $30M at auction and is in a private collection, but A Bigger Splash can be seen at Tate Britain. The spare composition and distinctive palette are his instantly recognisable trademarks.

A Bigger Splash by David Hockney (1967, Acrylic on Canvas, 242.5 × 243.9 cm, Tate Britain, London)

Update: here’s a very poignant cartoon by Ben Jennings.

What’s the French for Schadenfreude?

Posted in Astrohype, Biographical with tags , , , on June 12, 2026 by telescoper

Once upon a time – in the summer of 2022 – I posted a silly little joke on Twitter (before I left there, obviously):

I thought a few people might find it funny, but it took off beyond my expectations. By my standards over 5000 “likes” counts as “going viral” (as you young people say). Most people saw the joke immediately – if you don’t get it, the image is of a slice of choriz,o not an astronomical object – and some even joined in with puns and other jokes. Even funnier, some respondents earnestly shared their devastating insight that it was chorizo (or some variant thereof). I honestly didn’t think anyone would think that I was seriously trying to pass it off as a JWST picture; it was just meant to be silly. But there you go. That’s Twitter. I should also report that some people looked at the rainbow flags in my profile and proceeded to indulge in some homophobic abuse. That’s Twitter too.

Anyway, the day after I posted the image it seems a prominent French physicist called Etienne Klein who has many times more Twitter followers than I ever did, posted an embellished version of the same joke.

To cut a long story short that led to ChorizoGate, a story which made it into numerous newspapers, from the Daily Star to The Times, and even got coverage on CNN News and the RTÉ website. More exciting and even Physics World! In nearly all the stories I’ve seen, the image, together with the JWST connection, is attributed to Étienne Klein who is apparently very well known in France as a popularizer of science in the French language. Because he writes and broadcasts in French he is not so well known outside France.

In a post on this affair at the time, I said

To be honest I’m quite relieved to have avoided the media notoriety surrounding ChorizoGate, especially as it means I’ve avoided being on the front page of the Daily Star! Dr Klein is welcome to the publicity, though perhaps it might backfire on him…

And backfire it has.

Étienne Klein’s appropriation of a silly joke was of no consequence, but at the time I couldn’t help wondering how someone who would do that might behave with things that actually matter. Now I know the answer, and it’s more than worrying. An investigation into the PhD thesis of Etienne Klein by Paris Cité University has concluded that there is extensive evidence of plagiarism in it. Who needs AI when you have Etienne Klein? The University has now decided to rescind Klein’s doctorate, which was awarded in 1999.

What’s the French for Schadenfreude?

Euclid, Gravitational Lensing, and Dark Matter

Posted in Euclid, The Universe and Stuff with tags , , on June 11, 2026 by telescoper

I’ve been slow onto a result which was announced last week concerning the detection weak gravitational lensing in the cluster Abell 2390 by the Euclid spacecraft and its use to determine the distribution of dark matter in the cluster. You can find a full discussion of the result here and the scientific paper is here.

The analysis was based on Early Release Observations of the cluster, a pretty picture of which are shown here:

Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi.

(The little blue patches are artefacts caused by internal reflections in the VIS instrument and can be dealt with in software.)

According to general relativity, the presence of any mass bends the path of light passing near it, producing gravitational lensing. The most famous examples of this are the giant arcs and multiple images associated with strong gravitational lensing, but these are very rare as they require good alignment between observer, lens and source.. Most lines of sight in the universe do not satisfy this condition so are in the weak lensing regime. Even in such cases, however, the presence of the foreground mass can be detected, by way of a systematic alignment in the orientation of background sources around the lensing mass. A circular background image would be distorted into an ellipse by this process. Unfortunately galaxies aren’t circular but are approximately elliptical, so the shape of each source is changed from an ellipse to differently shaped ellipse. The distortion is therefore impossible to detect in a single background source because we don’t know the intrinsic orientation of the galaxy, but the distortion of different sources is correlated in a particular way. Weak gravitational lensing is thus an intrinsically statistical measurement, but it provides a way to measure the masses of astronomical objects without requiring assumptions about their composition or dynamical state. Weak gravitational lensing observations are, however technically difficult to carry out and analyse, as one has to be very careful that no correlations are introduced by systematic errors in the optics.

Anyway, they say that a picture paints a thousand words so here are two pictures. On the left we see the shear axes as extracted from the above image and on the right the inferred dark matter distribution. You can slide the bar backwards and forwards to see how the two images relate.

Shear map (left) and inferred dark matter distribution (right)

You can see that the shear tends to be aligned tangentially to a line connecting the image to the cluster centre (in the plane of the sky), which is what theory would predict.

There’ll be much more of this sort of analysis in the full Euclid Survey. I hope to be able to give an update about this reasonably soon.

Scéalta Grá na hÉireann – The Ladies of Llangollen

Posted in History, Irish Language, LGBTQ+, Poetry with tags , , , , , , on June 10, 2026 by telescoper

I just watched a nice documentary programme on the Irish language channel TG4 in the series Scéalta Grá na h’Éireann (Ireland’s Greatest Loves). This one was about Lady Eleanor Charlotte Butler and the Honourable Sarah Ponsonby, often called The Ladies of Llangollen. The programme is available on the TG4 Player, actually, and it is possible I think to watch the whole thing anywhere in the world for free here. There’s also a little trailer on Youtube:

There’s an entire wikipedia page devoted to the Ladies of Llangollen, so there’s no need to reproduce it all here. However, for the sake of you who haven’t heard of them, they were. They were of Anglo-Irish extraction, both born in Ireland, and had been brought up just a few miles away from each other. They met in 1768 and immediately hit it off. They ran off together to avoid being forced into unwanted marriages, and moved to Wales in order to set up home  at Plas Newydd, near Llangollen in Denbighshire, in 1780.

They lived together for the best part of 50 years in Plas Newydd, in relative seclusion, devoting their time to private studies of literature and languages and improving their estate, comprehensively redesigning the house in a Gothic style, and adding a superb garden. They did not actively socialise and town-dwellers of Llangollen seem to have regarded them as eccentrics, simply referring to them as “The Ladies”.

Gradually, their life attracted the interest of the outside world. Their house became a haven for all manner of visitors, mostly writers such as Wordsworth, Robert Southey, Shelley, Byron and Scott, but also the military leader Duke of Wellington and industrialist Josiah Wedgwood; aristocratic novelist Caroline Lamb, who was born a Ponsonby, came to visit too. Even travellers from continental Europe had heard of the couple and came to visit them, for instance Prince Hermann von Pückler-Muskau, the German nobleman and landscape designer who wrote admiringly about them.

The story of the “romantic friendship” between these two ladies is both charming and moving, but it’s also fascinating to learn how their lifestyle was accepted and even celebrated by wider society. One might have thought their relationship would have been regarded as scandalous by their contemporaries, rather than being widely admired as it turned out to be. One is tempted to assume that their  “marriage” had a sexual dimension, which it may well have done, but it could have been a platonic, yet still romantic, friendship. As far as I’m concerned, that doesn’t really matter;  what I find inspiring about them is that they dared to be different.

Anyway, here is the beautiful sonnet that William Wordsworth wrote after meeting the Ladies of Llangollen in 1824, although I believe the Ladies took exception to the description of their magnificent house as a “low-roofed cot”!

 A stream, to mingle with your favourite Dee,
Along the vale of meditation flows;
So styled by those fierce Britons, pleased to see
In Nature's face the expression of repose;
Or haply there some pious hermit chose
To live and die, the peace of heaven his aim;
To whom the wild sequestered region owes
At this late day, its sanctifying name.
Glyn Cafaillgaroch, in the Cambrian tongue,
In ours, the Vale of Friendship, let 'this' spot
Be named; where, faithful to a low-roofed Cot,
On Deva's banks, ye have abode so long;
Sisters in love, a love allowed to climb,
Even on this earth, above the reach of Time!