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Canada's NIRISS ready to see cosmos in over 2000 infrared colours

Canada's NIRISS instrument ready to disperse starlight

Test detector image of the NIRISS instrument operated in its SOSS mode while pointing at a bright star. Each colour seen in the image corresponds to a specific infrared wavelength between 0.6 and 2.8 microns. The black lines seen on the spectra are the telltale signature of hydrogen atoms present in the star. NIRISS is a contribution from the Canadian Space Agency to the Webb project that provides unique observational capabilities that complement its other onboard instruments. (Credit: NASA, CSA, and NIRISS team/Loïc Albert/University of Montreal)

One of the James Webb Space Telescope's four primary scientific instruments known as the Near-Infrared Imager and Slitless Spectrograph (NIRISS), provided by the Canadian Space Agency, has concluded its post-launch preparations and is now ready for science.

The last NIRISS mode to be checked off before the instrument was declared ready to begin scientific operations was the single-object slitless spectroscopy (SOSS) capability. The heart of the SOSS mode is a specialized prism assembly that disperses the light of a star to create three distinctive spectra (rainbows), revealing the hues of more than 2000 infrared colours collected simultaneously in a single observation. This mode will be specifically used to probe the atmospheres of transiting exoplanets, i.e. planets that happen to eclipse their star periodically, dimming the star's brightness for a period of time. By comparing the spectra collected during and before or after a transit event with great precision, one can determine not only whether or not the exoplanet has an atmosphere, but also what atoms and molecules are in it.

With NIRISS post-launch commissioning activities concluded, the Webb team will continue to focus on checking off the five remaining modes on its other instruments. NASA's James Webb Space Telescope, a partnership with the European Space Agency and the Canadian Space Agency, will release its first full-colour images and spectroscopic data on .

Abridged text reprinted courtesy of NASA

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