In the image factory of the “James-Webb”

Steps in the transformation of a raw image of the Orion Nebula, taken by one of the telescope's cameras, NIRcam.

On Monday, September 12, two new images from the James-Webb space telescope from American, European and Canadian agencies are released. They show two areas of the Orion Nebula, located in the constellation of the same name 1,350 light years from Earth, in our Milky Way. It is the closest to the nurseries of stars, these regions of gas, dust and stars where stars are still born and where researchers hope to find analogues of what was our solar system in formation. Colourful, textured, as if animated by the movements of storms or bubbling waters, these two images are dazzling. And amaze. Why do we see something when the radiation detected by the telescope is invisible, because it is located in the infrared. Immerse yourself in the making of these images, over twenty-four hours.

Saturday, September 10, 9 p.m. The 6.5-meter mirror of the James-Webb, located 1.5 million kilometers from Earth, pivots imperceptibly to aim at the Orion Nebula, after having captured the light of the white dwarf G191-B2B. For two hours fifty-seven minutes, one of the four instruments, Nircam, captures the precious grains of light emitted by M42, the precise name of the nursery.

Sunday, September 11, 12:40 a.m. The results are transmitted to the public MAST database of the Space Telescope Science Institute (STScI) from the United States. Surprise: the images are really ugly. In black and white, streaked, blurred…

Read also: What the spectacular images of the James-Webb telescope reveal

9 hours. In Toulouse, the person in charge of the 1288 program dedicated to Orion, Olivier Berné (Institute for research in astrophysics and planetology), sounds the recall of the troops to make speak these images which he has been waiting for at least five years. His two fellow research engineers, Amélie Canin and Ilane Schroetter, spin to the laboratory. They start downloading the data… on the porch, their badge not working on Sunday. Their manager, endowed with sesame, arrives accompanied by a central actress for the day's activity, Salomé Fuenmayor, a young Spanish graphic designer, responsible for transforming the initial ugliness into universal beauty.

The color image was obtained using three filters.

11:30 a.m. Ilane turns the coffee grinder as she grinds the stimulating beverage by hand. In front of their two screens, one reproducing the lines of code to be applied, the other the results, the engineers know exactly what to do to process the very many images sent during the night. The telescope indeed did not take only one shot but dozens. First, because his camera simultaneously targets two regions of Orion. Then because each of these shots is in fact divided into 14 filters, corresponding to different parts of the infrared spectrum, from 0.6 to 5 micrometers. Finally, for each filter, several images are taken shifted by a few pixels, to eliminate faulty points and improve resolution. That is a total of 280 images to be processed.

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