“Mechanical images of stars with a strong focus on the field of view of each instrument show that the telescope is fully aligned and focused,” writes the European Space Agency. “For this test, Webb showed part of the Large Magellanic Cloud, a small satellite galaxy of our galaxy, providing a dense field of hundreds of thousands of stars to all of the observatory’s sensors. The sizes and positions of the images shown here illustrate the relative arrangement of each of Webb’s instruments in the telescope’s focal plane, each pointing slightly at one of the skies relative to each other. Mechanical images of stars with a clear focus on the field of view of each instrument show that the telescope is fully aligned and focused. NASA / STScI These four instruments are the Mid-Infrared Instrument (MIRI), the Near-Infrared Camera (NIRCam), the Near-Infrared Spectrograph (NIRSpec) and the Near-Infrared Imager and Slitless Spectrograph / Fine Guidance Sensor (NIRISS / FGS) . ). These are three imaging instruments and a spectrograph (an instrument for detecting the composition of objects by separating the light they emit), but the spectrograph can also be used to capture images – such as the images shown above used for calibration and target selection. If you look at the NIRSpec image, you will see black bands along it, caused by the micro-aperture device that allows it to open and close tiny windows so that the instrument can see up to 100 objects at a time. All four instruments are aimed at the same target so that engineers can check that they were all as sharp and accurate as needed. And the results are even better than the engineers expected, resulting in a high degree of image quality which means the instruments are confined to diffraction – meaning they receive as much detail as possible for the size of the telescope. Once the alignments are complete, the team can now start operating each instrument. This includes shaping and inspecting parts of instruments, such as masks and filters, to make sure they are ready for scientific work. Some final telescope calibration procedures are also required, such as checking that the telescope remains at a constant temperature when moving from one target to another. Once all this is done, the telescope is scheduled to begin scientific operations this summer.

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