Since the launch of the James Webb Space Telescope last December, engineers have been working to deploy the telescope’s hardware and then align both mirrors and tools. Now this multi-month process has been completed and it has been confirmed that the telescope is completely aligned. NASA and the European Space Agency have shared an image showing the sharpness of all Web tools, which shows that they are all clear and properly focused.
“Engineering images of sharply focused stars in the field of view of each instrument show that the telescope is fully aligned and in focus,” wrote the European Space Agency. “For this test, the Web pointed to part of the Large Magellanic Cloud, a small satellite galaxy in the Milky Way that provides a dense field of hundreds of thousands of stars through all of the observatory’s sensors. The dimensions and positions of the images shown here depict the relative position of each of the Web instruments in the focal plane of the telescope, each pointing to a slightly offset part of the sky relative to each other.
Engineering images of sharply focused stars in the field of view of each instrument show that the telescope is fully aligned and in focus. NASA / STScI
The four instruments in question are the Medium Infrared Instrument (MIRI), the Near Infrared Camera (NIRCam), the Near Infrared Spectrograph (NIRSpec) and the Near Infrared Image and Slotless Spectrograph / Fine Direction Sensor (NIRISS / FGS). These are three imaging instruments and one spectrograph (an instrument for detecting the composition of objects by dividing the light they emit), but the spectrograph can also be used for imaging – such as the images shown above, which are used for calibration and targeting selection. If you look at the NIRSpec image, you will see black bars on it, which are caused by its micro-shutter, which allows it to open and close small windows so that the tool can monitor up to 100 objects at a time.
All four tools are aimed at the same goal so that engineers can check that they are all as sharp and accurate as they need to be. And the results are even better than the engineers hoped, resulting in a high degree of image quality, which means that the instruments have limited diffraction – which means they get the maximum possible amount of detail for the size of the telescope.
Once the alignment is complete, the team can now start commissioning each tool. This includes configuring and testing parts of tools, such as masks and filters, to make sure they are ready for scientific operations. Some final processes of calibration of the telescope are also needed, 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 should begin scientific operations this summer.
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