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How a small team in Baltimore brought the Webb telescope’s images to life


From its orbit a million miles from Earth, the now operational James Webb Space Telescope has finally returned its first images, including a deep field view of 1000’s of galaxies, shining like gems billions of sunshine years away. But as stunning as those images are, they’d be nothing but an array of black pixels without passing through the Steven Muller Constructing, a modest khaki-brick structure tucked into the trees on the Johns Hopkins campus in Baltimore, Maryland.

There are few everlasting features alerting the casual passerby that the constructing is the headquarters of the Space Telescope Science Institute, (STScI), though a blue and gold banner hung over the important entrance proclaiming “Go, Webb, Go!” provides an obvious clue. STScI began operating the Hubble Space Telescope on behalf of Nasa and scientists in 1990, and the institution’s mission has now expanded to incorporate Webb. STScI controllers helped guide the brand new space telescope through the deployment and commissioning process, and in early June, began taking the primary images with the massive gold telescope.

And people images don’t magically appear in good color and balanced brightness. The raw data captured by Webb have to be processed, cleaned of artifacts, and colourised by specialists at STScI who work behind the scenes to process all Webb images released to the press through the years the telescope does science. And it’s in some ways an inventive process as much as a technical one.

Shedding light

On 24 June, roughly two weeks before the primary Webb images could be released to the general public, science visuals developers Joseph DePasquale and Alyssa Pagan sat of their shared office surrounded by large computer screens, demonstrating how they processed the very first Webb images beamed back to Earth. With the flick of a mouse, Mr DePasquale took the primary Webb deep field image, an array of glowing gems, actually 1000’s of incredibly distant galaxies, and returned the image to the best way it got here to him: a black screen.

“The pixel values are mostly dark, since the sky is generally dark, and only the brightest regions show through once you see it at first,” he said. Mr DePasquale and Ms Pagans’ task is to make use of a set of software to boost the brightness of the image to permit people to see the darkest details, without washing out the brilliant regions. “All this information is hidden in here, since it’s really very dim.”

Webb’s spectrum for the exoplanet Wasp-96b, essentially the most detailed exoplanet spectrum yet taken, show multiple water vapor features


With a number of more clicks on the keyboard, Mr DePasquale raises the brightness in a process often called “scaling” the information, revealing a grayscale version of the Webb deep field. Adding color is available in a later step, but that must wait until Mr DePasquale deals with one other problem introduced by scaling the image to make it brilliant enough to see.

“Vibrant stars in Webb will are likely to saturate to the purpose where the detector not gives you valid information,” Mr DePasquale said. “When that runs through the pipeline, you find yourself getting a black hole within the centre of a brilliant star.”

This effect will be seen within the Webb image released on 6 July as a sneak peek, an orange-hued star-field captured by the space telescope’s guidance instrument. On the centres of brilliant, spiky stars are black circles looking like holes burned through a movie negative.

“We were sweating this out as we were getting closer and closer to the [Webb image release] date,” Mr DePasquale said, but he eventually hit on a pc script that may fill within the black holes with the values of neighbouring pixels. It’s the kind of novel solution required with the Webb data, he adds, because unlike the familiar workflow for developing images from Hubble data, with Webb “the method is kind of in flux immediately because the whole lot is recent.”

Which Webb first?

The Webb deep field image was the primary of 5 images chosen by STScI and Nasa to indicate the tangible results of the greater than 20 years and $10 billion it took to design, develop, construct, test, launch, deploy, configure and commission essentially the most sophisticated telescope ever constructed. US President Joe Biden previewed the deep field image from the White House on 11 July, while the remaining 4 images were revealed the next morning through Nasa’s website. The complete set of images includes the deep field, the spectrum, or pattern of sunshine filtered through the atmosphere of the exoplanet Wasp 96 b, and pictures of the Carina nebula, the Southern Ring Nebula, and Stephan’s Quintet, a group of 5 galaxies locked in a decent gravitational dance.

But as of 24 June, what images the general public would see first, and exactly what they’d appear like, was still a matter of debate.

“The charter we’ve is to show to the world that the observatory is able to do science, to have a good time that it’s able to do science,” said Klaus Pontoppidan, an associate astronomer at STScI. He was certainly one of a few dozen people in a small conference room on 24 June to debate the photographs to be released to the general public.

“Almost no person else on this constructing and even at NASA has seen this,” Dr Pontoppidan added. “It’s just this room.”

Astronomer Karl Gordon, science visuals developers Alyssa Pagan and Joseph DePasquale, and astrophysicist Anton Koekemoer discuss Webb Telescope image processing on the Space Telescope Science Institute in Baltimore.

(Stsci/Jackie Barrientes)

The small group had been meeting most mornings all month to debate the newest images and processed by Mr DePasquale and Ms Pagan and displayed on an enormous wall-hung monitor. On 24 June, the discussion turned to which version of the Carina nebula image would make the general public release, a picture taken with Webb’s near-infrared instrument, NIRcam, or its mid-infrared instrument, MIRI.

Webb captured images of the Southern Ring Nebular in near-infrared (left) and mid-infrared (right) light.

(NASA, ESA, CSA, STScI, and The E)

While the NIRCam image highlighted the orange and gold dust clouds, MIRI peered through the dust to disclose more stars, but with the gas clouds showing up in shades of greyish blue against a red “sky,” a controversial aesthetic.

“To me, the greyish blue, the best way it turned out on the MIRI image, that is just not attractive,” got here certainly one of many overlapping comments within the room.

But there was a  third option presented by Mr DePasquale and Ms Pagan — a mixture of NIRCam and MIRI imagery, a mix of perspectives preserving the contrast of the MIRI image while overlaying the numerous details and stunning colors of the NIRCam image.

“It’s like one of the best of each worlds,” Ms Pagan said.

The group ultimately settled on the Carina combination image, which is what the general public saw on 12 July.

Color coordination

However the creation of the Carina image highlights one other way wherein creating visible images from Webb’s data is a creative process in its own right, particularly with regards to the color process.

Step back to the proven fact that most raw Webb images are essentially blank to the human eye. The distant objects it images are in lots of cases incredibly faint, too faint to register in the color perceiving cone cells within the human eye. That’s often true even with less exotic astronomical observations.

“Leaf through a telescope at a planet like Jupiter or Saturn, and it looks almost black and white, because the sunshine is so dim that it’s really only activating the rods in your eyes and never the cones,” Mr DePasquale said. “You’re probably not getting color information.”

In Webb’s case, add to that the proven fact that the telescope sees only in infrared, wavelengths of sunshine too long for human eyes to see in any respect, regardless of how brilliant. To make Webb’s images visible then, Ms Pagan and Mr DePasquale must transpose frequencies of sunshine invisible to human eyes into the visible portion of the spectrum.

“Telescopes are designed with filters to separate out the several colors, after which we assign those colors chromatically,” he said. “The shortest wavelengths of sunshine are assigned to blue colors, then you definately move from blue to green to red as you increase wavelength.”

That’s a system that worked well with Hubble, that saw only into the near-infrared, and up to now seems to work well for Webb’s NIRCam, in keeping with Ms Pagan.

Stefan’s Quintet, a visible collection of 5 distant galaxies, was certainly one of the Webb Telescope’s first full-colour images


“But once we go into the mid-infrared with MIRI what we’re getting could be very different, which is a challenge,” she said. To avoid garish color combos just like the MIRI image of Carina, they’d to get just a little creative with the color mapping, “so it is perhaps red, orange and cyan” reasonably than red, green and blue.

The method is perhaps entirely different for scientists using Webb to review a selected aspect of a distant object, Ms Pagan noted. Moderately than attempting to transpose non-visual wavelengths of sunshine into the visible spectrum in a way that makes visual sense, a researcher might request color highlighting based on some phenomenon of interest, equivalent to organic gas clouds. Researchers might also call upon their office’s services when publicizing the outcomes of their research with Webb.

“There’s an online page for scientists to submit their proposals for a press release,” Mr DePasquale said. “They’ll undergo that avenue, contact the news office here, after which we’ll determine if it’s actually press worthy. In that case, then it involves us to process the information.”

The processing will be lots of work, especially with Webb — developing the Carina Nebula image took 16 hours — and Ms Pagan and Mr DePasquale worked through weekends in the times leading as much as the discharge of the primary Webb images. However the work can be so charming, they’d have processed the brand new images even without the urgency of the upcoming public release.

“The primary data set got here in on a Saturday morning, and I needed to drive as much as Philly for a family party,” Mr DePasquale said. “I’m on the party. And I’m like, ‘I just need to be working on that image.’”

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