This test image of the thin guide sensor was acquired in parallel with the NIRCam image of the star HD147980 over a period of eight days in early May 2022. This engineering image represents a total of 32 hours of time of exposure at various overlapping points of the Guider 2. channel. The observations were not optimized for the detection of weak objects, however, the image captures extremely weak objects and is, for the time being, the deepest image of the infrared sky. The guide’s unfiltered wavelength response, 0.6 to 5 micrometers, helps provide this extreme sensitivity. The image is monochrome and is shown in false color with white-yellow-orange-red representing the progression from brightest to faintest. The bright star (at a magnitude of 9.3) on the right edge is 2MASS 16235798 + 2826079. There are only a handful of stars in this image, which are distinguished by their diffraction peaks. The rest of the objects are thousands of faint galaxies, some in the near universe, but many, many more in the far universe. Credits: NASA, CSA and FGS team.
We’re just five days away from the July 12 release of the first full-color images of NASA’s James Webb Space Telescope, but how do you find the observatory and set your sights on it? Webb’s thin guide sensor (FGS) was designed with this particular question in mind. (The FGS, as well as the Near-Infrared Imager and Slitless Spectrograph (NIRISS), were developed by the Canadian Space Agency.) Recently, FGS captured a view of stars and galaxies that offers a tempting view of what the scientific instruments of the JWST. in the coming weeks, months and years.
Although the main goal of the FGS is to enable accurate scientific measurements and imaging with precision aiming, it has always been able to capture images. When it does, images are not usually preserved: given the limited bandwidth of communications between L2 and Earth (a distance of 1.5 million kilometers), Webb only sends data from up to two scientific instruments at a time. However, during a stability test for a week in May, it occurred to the computer that data transfer bandwidth was available, so that they could retain the images that were being captured.
The James Webb Space Telescope will be the most important space observatory of the next decade, serving astronomers around the world. One of the two Canadian elements of the James Webb Space Telescope, the FGS is the most sophisticated guide sensor of any telescope ever built. It sticks to bright stars in deep space to keep Webb images sharp. Credit: CSA
The resulting engineering test image (shown at the top of this article) has some approximate qualities. It was not optimized to be a scientific observation; rather, the data was taken to test the extent to which the telescope could remain locked to a target, but hints at the power of the telescope. It carries some of the features of the views that Webb has produced during its post-launch preparations. The bright stars stand out with their long, well-defined six diffraction spikes, an effect due to Webb’s six-sided mirror segments. Beyond the stars, galaxies fill almost the entire background.
According to Webb scientists, the result, using 72 exposures for 32 hours, is among the deepest images in the universe ever taken. When the FGS aperture is open, it does not use color filters like other scientific instruments, which means that it is impossible to study the age of galaxies in this image with the rigor necessary for scientific analysis. But even when capturing unplanned images during a test, FGS is able to produce stunning views of the cosmos.
The thin guide sensor (FGS) allows Webb to aim accurately, so you can get high quality images. The Near Infrared Imager and Slitless Spectrograph part of the FGS / NIRISS will be used to investigate the following scientific objectives: first light detection, exoplanet detection and characterization, and exoplanet traffic spectroscopy.
FGS / NIRISS has a wavelength range of 0.8 to 5.0 microns and is a specialized instrument with three main modes, each of which is aimed at an independent wavelength range. FGS is a “guide” that helps aim the telescope.
“With the Webb telescope achieving better image quality than expected, at the start of the launch we intentionally blurred the guides a small amount to help ensure they meet their performance requirements. When this was done image, I was thrilled to see clearly the entire detailed structure of these faint galaxies.Given what we now know is possible with deep broadband guide images, perhaps these images, taken in parallel with other observations when if feasible, they could prove scientifically useful in the future, “Neil Rowlands, a scientist in Webb’s thin guide sensor program, told Honeywell Aerospace.
Because this image was not created with a scientific result in mind, there are some features that are quite different from the full-resolution images that will be released on July 12th. These images will include what it will be, at least for a short period of time. – the deepest image of the universe ever captured, as announced by NASA administrator Bill Nelson on June 29th.
The FGS image is painted with the same reddish color scheme that was applied to the other Webb engineering images during startup. Also, there was no “heat” during these exhibitions. Dithering is when the telescope is repositioned slightly between each exposure. In addition, the centers of bright stars appear black because they saturate Webb detectors, and the telescope’s focus did not change with exposures to capture the center of different pixels within the camera’s detectors. The overlapping frames of the different exhibits can also be seen at the edges and corners of the image.
In this engineering test, the purpose was to look at a star and test the extent to which Webb could control its “roll,” literally, Webb’s ability to roll to one side like an airplane in flight. This test was successfully performed, in addition to producing an image that awakens the imagination of scientists who will analyze Webb’s scientific data, said Jane Rigby, Webb’s operations scientist at NASA’s Goddard Space Flight Center in Greenbelt. Maryland.
“The faintest spots in this image are exactly the types of faint galaxies Webb will study during his first year of scientific operations,” Rigby said.
While Webb’s four scientific instruments will reveal the new vision of the telescope universe, the thin guide sensor is the only instrument that will be used in every Webb observation throughout the life of the mission. FGS has already played a crucial role in aligning Webb’s optics. Now, during the first actual scientific observations made in June and once scientific operations begin in mid-July, he will guide each Webb observation toward its goal and maintain the accuracy necessary for Webb to produce innovative discoveries about stars, exoplanets, galaxies, and even and everything. moving targets within our solar system.