How the James Webb telescope images were brought to life


Erik Rosolowsky was like a child at Christmas when the James Webb House Telescope began sending him long-awaited pictures of a distant galaxy.

And the primary particular person he needed to point out his new current to was his Uncle Mike.

Rosolowsky, an affiliate professor of physics on the College of Alberta, was among the many first Canadian researchers to place the world’s newest and best house telescope to make use of, in his case, by observing star formation within the Triangulum Galaxy, often known as Messier 33.

“When my undertaking was executing, I used to be pulling (knowledge) out of the archive as quickly because it was touchdown,” says Rosolowsky. “I despatched an image of it to my uncle … ‘Hey Uncle Mike! You and I are the primary folks on Earth to see these footage!’ ”

His Uncle Mike, a yard astronomer, is the one that first set Rosolowsky on the trail that finally led him to obtain photos of a galaxy two million mild years away from a $10-billion telescope orbiting the solar, some 1.5 million kilometres away from Earth.

However the image Rosolowsky despatched to Uncle Mike — vital because it was for them each — was a far cry from the beautiful full-colour photos launched by NASA because the JWST continues to assemble popularity of its high-resolution infrared observations of the universe.

As a substitute, the image for Uncle Mike — just a few mild blobs on a darkish background crisscrossed with banding — regarded one thing like this:

That stands in stark distinction — actually — to the well-known Hubble picture of Triangulum, and even Rosolowsky’s partially processed Webb picture, each of which present hundreds of thousands of stars, the spiral arms of the galaxy and, within the latter’s case, among the turbulent areas the place stars are born.

A stunningly detailed portrait of the Triangulum Galaxy (M33), displaying a full spiral face aglow with the light of nearly 25 million individually resolved stars, as captured by NASA's Hubble Space Telescope. It is the largest high-resolution mosaic image of Triangulum ever assembled, composed of 54 Hubble fields of view spanning an area more than 19,000 light-years across.
A view of the Triangulum Galaxy (M33), two million light years from Earth, as captured by the James Webb Space Telescope (JWST) and processed by Canadian astronomer Erik Rosolowsky.

The distinction between the photographs illustrates the hassle that researchers make to translate uncooked knowledge from the JWST into photos that astronomers can use for analysis and people at which most people has marvelled.

In fact, Rosolowsky’s preliminary knowledge — a part of an precise astronomical picture because it seems in his pc code — regarded one thing like this:

A portion of an image of the Triangulum Galaxy (M3), two million light years from Earth — as captured by the James Webb Space Telescope — is shown as raw data, as it appears in Canadian astronomer Erik Rosolowsky's code.

What he despatched to his uncle, he says, was a “fast and soiled look” on the Triangulum Galaxy.

However earlier than these photos — or that knowledge — can change into remotely helpful to him as a researcher, they must be corrected, not the least for quirks inherent within the tools.

For all of the meticulous precision that went into the JWST’s design and building, the information coming from it, in its rawest type, is uneven.

Pictures must be corrected for imperfections inherent within the cameras themselves.

Cosmic rays hitting the telescope can create static within the detectors of its cameras, which is corrected for, partially, by capturing a number of variations of the identical picture.

And even the pixels — the smallest photosensitive models of the telescope’s detectors — themselves have completely different sensitivities; one of many a couple of million pixels within the JWST’s Mid-Infrared Instrument (MIRI), for instance, could be extra delicate than its neighbour, and fewer delicate than one other neighbour.

Fortunately, the JWST engineers have an answer for that — a whole calibration map of the way to compensate for the variations in every pixel in each instrument on the Webb telescope.

“That is the work of a whole lot of individuals,” says Rosolowsky. “After we say ‘commissioning a telescope’ — it launched after which they went by way of this era the place you heard nothing in regards to the outcomes.

“That’s what they had been doing up there. It’s lastly turned on. They’re beginning to make photos and say, ‘How can we take out all these corrections?’ ”

All he has to do, he says, is apply the JWST’s map of pixel calibrations to his knowledge to account for these variations in pixel sensitivity.

For many researchers, a lot of this technical work takes place in what they universally name “the pipeline.”

Consider it as a data-processing freeway, the place the uncooked knowledge acquired from the JWST is refined because it travels from supply to vacation spot.

Alongside the size of that freeway, some software program processing modules would possibly apply corrections to the information primarily based on inconsistencies or aberrations within the detectors, others would possibly apply corrections primarily based on calibrations for the cameras themselves, and but others would possibly mix the information from a number of exposures into single photos.

However the freeway additionally has a collection of off-ramps, from which researchers can extract their info at earlier phases of the processing for his or her extra particular makes use of.

In Rosolowsky’s case, he desires a few of that uncooked knowledge, nearer to the start of the pipeline.

It’s all nicely and positive to have one thing good to ship to a cherished one, says Rosolowsky, however researchers don’t do science off of fairly photos.

A lot of his work is completed with the uncooked, numerical knowledge.

“The gorgeous footage are great for deciphering and build up and telling a narrative,” he says. “However then backing up that story is what requires doing the pc processing to determine the way to measure each star on this picture, work out what it’s, after which use that to again up your declare.”

“Most of my job is programming, so I’m writing the pc code that’s going to take this huge chunk of numbers and switch this into properties of stars,” he says. “That’s my day job whenever you get all the way down to it.”

‘It was beautiful, actually’

It’s a special state of affairs for Alyssa Pagan, although. She works with NASA as a science visuals developer. She’s one of many folks accountable for processing the beautiful photos from the Webb telescope launched to the general public.

In actual fact, the picture of the “Cosmic Cliffs” of the Carina Nebula, considered one of the primary 5 photos launched from the JWST, was the primary she’d labored on from the Webb.

“It was insane,” she says of engaged on the primary photos from the Webb. “It was beautiful, actually, to me from the get-go.”

“The truth that you’re one of many first folks to see the picture and … course of it and put it out for the general public — it was an enormous honour. And it was additionally a time to replicate on how far we’ve come, and all of the folks concerned to make it potential.”

For Pagan, the photographs she started to work with had been retrieved from additional down the pipeline — with a lot of the compensations and artifact elimination already achieved.

In actual fact, the Carina Nebula picture was a composite of six monochrome photos, captured with six completely different filters, every exhibiting the nebula in a barely completely different wavelength of infrared, which is the Webb telescope’s milieu.

However the uncooked photos she started to work on weren’t a lot to have a look at — just a few specks of white on a darkish subject, no element in any respect.

That’s as a result of the dynamic vary of the JWST cameras — the distinction between the blacks and the whites within the photos — was far an excessive amount of for even Pagan’s high-end pc screens to register. The data — the element at the hours of darkness components of the picture — existed, however her screens weren’t in a position to understand it.

Images of the Carina Nebula captured at various infrared wavelengths by the James Webb Space Telescope are shown before processing.

The answer was to compress that dynamic vary — convey the blacks and whites nearer collectively — in order that it will match inside the vary of her monitor. Considerably confusingly, that is referred to as “stretching” the picture.

Images of the Carina Nebula captured at various infrared wavelengths by the James Webb Space Telescope are shown after compression of their dynamic ranges.

Submit-stretching, she was in a position to see element within the photos — most of the fainter stars and the cloud of mud and gasoline that characterize a nebula. However she was nonetheless a collection of black and white photos — the subsequent step was to assign colors to every of these photos. This isn’t completed in random trend.

How your mind understands mild

What we people understand as seen mild is however a small part of the electromagnetic spectrum, that portion to which our eyes are delicate. To at least one finish of that part, the part the place mild has shorter wavelengths, our mind assigns the bluish colors. To the opposite finish of the part, that which incorporates the longer wavelengths, it assigns reddish colors.

On both facet of the part of the spectrum to which our eyes are delicate are wavelengths that our eyes can’t detect, however which, in some instances, different animals — or specifically designed devices — can.

The Webb telescope operates within the infrared vary of spectrum; that’s, previous what we see as pink, within the part of spectrum with longer wavelengths than we’re in a position to understand. That has benefits by way of astronomy; infrared mild can typically pierce clouds of mud and gasoline that might block seen mild.

Nevertheless it implies that to see what the Webb has noticed, we have now to create a illustration of every picture that falls inside that portion of the electromagnetic spectrum to which our eyes are delicate — the seen mild part.

And so as to add color to these photos, Pagan adopted roughly the identical conventions that our mind does — shorter wavelengths are assigned bluish colors, longer ones get reddish colors.

Images of the Carina Nebula captured at various infrared wavelengths by the James Webb Space Telescope are shown after dynamic range compression and with colours assigned to wavelengths

When that was completed, she may stack these colored photos on high of one another to make one full-colour picture.

A full-colour image of the Cosmic Cliffs of the Carina Nebula ? created by stacking a series of images captured at various infrared wavelengths by the James Webb Space Telescope ? is shown before final processing.

At this level, she says, she begins balancing science with esthetics.

“That’s the place it turns into fairly subjective,” she says. “We’re working with scientists by way of this course of … to verify we’re showcasing the information as a lot as potential and we’re being as trustworthy as potential.

“However it’s subjective now as a result of we’re adjusting like tonality and distinction, color and all this stuff to actually make the options in every filter extra distinguished or simply to showcase and spotlight these completely different areas.”

Working in Photoshop, Pagan tweaked the picture to provide one thing each esthetically pleasing — “natural” is the time period she likes to make use of — and scientifically correct.

A full-colour image of the Cosmic Cliffs of the Carina Nebula ? created by stacking a series of images captured at various infrared wavelengths by the James Webb telescope ? is shown after final processing.

On its launch by NASA, on July 12, the Carina Nebula picture wowed astronomy buffs and scientists alike, a lot of whom had been ready many years to see the depths of the universe by way of the eyes of probably the most highly effective telescope ever constructed.

It was, within the phrases of Canada’s JWST scientific director René Doyon, “the gorgeous bridge between science and artwork.”

“It’s so cool to see everybody speaking about it,” says Pagan. “It appears like a pleasant, linked, common second of appreciation for science and humanity.”


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