James Webb Space Telescope Reaches First Photons

The largest and most powerful telescope ever built in the world, the James Webb Space Telescope completed its journey and settled in L2 orbit, 1.5 million km away. After successfully completing its journey, the telescope opened all its mirrors after it sat on its orbit in L2. There are 18 individual mirrors on the James Webb surface, and these mirrors must move as one whole mirror. With 0.54 nanometer adjustments, the mirrors will work as a single whole. Since our perception of small and large numbers is somewhat difficult, NASA explains this with an analogy: “If this telescope's primary mirror, which would act as a single surface, was US-sized, every mirror segment that makes up it would be the size of Texas. The team would have to align the height of these Texas-sized mirrors. With a margin of error of 4 cm…”. For our understanding, we can translate it as follows; Turkey is almost as big as Texas, 1.2 times its size… Even if the size of the 18 mirrors were the size of these cities, the margin of error should have been smaller than 4 cm. Since there are very complex adjustments, adjustments will be made in 7 separate stages. In addition, Nasa will perform these stages on a small prototype.

What kind of adjustment do you think can be used to make these adjustments? First they have to adjust the mirrors as one whole. These mirrors then need to focus their image on a single star. The telescope succeeded in superimposing the photographs taken one by one. HD 84406. Each of the 18 mirrors was aimed at this star, 258.5 million light-years away. The first photons, which have been on the road for millions of years, have arrived. Scientists immediately began to analyze these first images, which came at midnight, and showed that the first phase of the calibration process had been successfully completed, based on the first photons that reached them.

The star, known as HD 84406 in the Ursa Major Constellation, was especially chosen. It is easily visible as it is not surrounded by other stars of similar brightness. There are no stars in the background to blur the image. The points in this mosaic are labeled according to the primary mirror fragment. So you're currently looking at 18 separate images of the same star captured with different mirrors.

During the image capture process, which began in February, JAMES WEBB was reoriented to 156 different positions 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. The images were then individually linked together to create a single, large mosaic that captures the signature of each primary mirror piece in a single frame. The image is only the middle part of a huge mosaic with over 2 billion pixels.

Most Important Stage

In the final stage, the individually aligned mirrors will be micro-adjusted to form a single image. The first scientific images, perhaps images of the earliest times of our universe, are expected to reach Earth in the summer.

The first photons to arrive from the Ursa Major confirmed Webb's functions, and this is of course an important detail. Much remains to be done in the coming months to begin scientific observations using all four instruments on James Webb.