The first photons have reached the WEBB Space Telescope!
The James Webb Space Telescope, the largest and most powerful telescope ever, completed its journey and settled in its orbit 1.5 million km/932 056.7miles away. After completing all the stages it had to perform, its mirrors were finally opened. Now, these mirrors need to be calibrated. A total of 18 mirrors need to be adjusted with a precision of 50 nanometers.
Since small and large numbers are somewhat difficult for us, NASA explains this with the following: “If this telescope's primary mirror, were the size of the US, each mirror segment would be the size of Texas, and the team would have to align the height of these Texas-sized segments. With a maximum margin of error of 4 cm." We can compare this to Turkey. Since Turkey is almost the size of Texas, 1.2 times its size! Even if each of these 18 mirrors were the size of a country, the margin of error should have been less than 4 cm/ 1.57 inches. These adjustments are being made. Since it is a complex process, it will be carried out in a total of 7 phases.
Each of these stages is first rehearsed on a scaled-down model, and then signals are sent. So, what method do you think can be used to make such an alignment? The first method is to direct the mirrors to a single target and overlap the dots in the photographs. The telescope did that too. One of the stars in the Ursa Major constellation was chosen: HD 84406. Each mirror was directed at this star, which is 258.5 million light-years away. And the first photons, which had been on the way for millions of years, reached the telescope. Scientists began to analyze these images, which came around midnight. And starting from these first photons, they saw that the first phase of the calibration process had been accomplished.
The star Known as HD 84406 in the Ursa Major Constellation, was specially selected. It is easily visible because it is not filled with other stars of similar brightness around it. There is no background crowd to blur the image. Each point within this mosaic is labeled according to the primary mirror fragment that captured it. So we're currently looking at 18 separate images of the same star captured with different mirrors. In other words, this tool initially behaved as if it consisted of 18 separate smaller telescopes. During the image capture process, which began on February 2, WEBB was reoriented to 156 different locations around the estimated position of the star and captured 1,560 images of 54 gigabytes of raw data using the 10 detectors of the onboard NIRCam camera. This whole process took about 25 hours. These images were then linked together to create a single, large mosaic that capture the signature of each primary mirror piece in a single frame. The images shown here are just the middle section of a huge mosaic with over 2 billion pixels.
The 18 seperate dots we see are images captured by 18 seperate mirrors, that act like little telescopes. Images from the right and left wing from the telescope are circled in this image here, The fact that the first mosaic was left on the edges is exactly the result that scientists expected and thought to happen at the beginning. After matching the dots with the mirrors, a series will be made. Then, the global alignment phase will begin. Each of the 18 dots will be aligned and focused. On the left we see the expected result in the 1/6 scale test model. In the most important and final stage, these individually aligned mirrors will be micro-adjusted to form a single image. By the way, WEBB also took a selfie and sent it. This "selfie" was created using a special lens inside the NIRCam device, which is designed to capture images of primary mirror segments rather than images of space.
This lens is placed to make sure that they are in the correct route for engineering and alignment purposes only, not for scientific operations. In the photo, one of the mirrors appears bright because at the time they pointed only that mirror at a star. In this way, the shapes and edges of other mirrors were successfully displayed. If you’d notice the instrument itself appears in the middle. Thanks to such photos showing the telescope, scientists will be able to monitor how the alignment and calibration processes are progressing.
These are the first fragments of images taken by the telescope. However, These are specifically for engineering purposes only, as I mentioned during the broadcast and video I prepared at the end of last year, we still have a few months to reach the images that will be taken for scientific purposes. In this process, the other three instruments on the telescope must reach their cryogenic operating temperatures. The first scientific images are expected to reach the world in the summer months.
Both the selfie taken and the first photons from the Ursa Major confirmed Webb's functions, and this is of course an important milestone. Much remains to be done in the coming months to begin scientific observations using all four instruments on WEBB.
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