Webb advances an appetizer of the best image in the universe

July 7. () –

The Webb Space Telescope’s Fine Guidance Sensor (FGS) has provided a view of stars and galaxies, preview of what the observatory’s instruments will begin to reveal on July 12.

FGS has always been capable of capturing images, but its primary goal is to enable precise scientific measurements and accurate pointing imaging. When it captures images, they are typically not preserved: Given the limited communications bandwidth between L2 and Earth, Webb only sends data from up to two science instruments at a time. But during a week-long stability test in May, it occurred to the team that they could keep the images being captured because data transfer bandwidth was available.

The resulting engineering test image has some rough qualities. It was not optimized to be a scientific observation; rather, the data was taken to test how well the telescope could stay locked on a target, but it does hint at the power of the telescope.

It carries some features of the views that Webb has produced during its post-launch preparations. The bright stars stand out with their six long, sharply defined diffraction peaks, an effect due to Webb’s six-sided mirror segments. Beyond the stars, galaxies occupy almost the entire background.

The result, using 72 exposures over 32 hours, is among the deepest images of the universe ever taken, according to Webb scientists. When the FGS aperture is wide open, it doesn’t use color filters like the other science instruments, which means it’s impossible to study the age of the galaxies in this image with the rigor needed for scientific analysis. But even when shooting unplanned images during a test, FGS is capable of producing stunning views of the cosmos.

THE BEST IMAGE OF THE UNIVERSE ARRIVES ON JULY 12

Because this image was not created with a scientific outcome in mind, there are some features that are quite different than full resolution images which will be published on July 12. Those images will include what will be, at least for a short time: the deepest image of the universe ever captured, as announced by NASA Administrator Bill Nelson on June 29.

The FGS image is colored with the same reddish color scheme that was applied to the other Webb engineering images during commissioning. Also, there was no “hesitation” during these exposures. Dithering is when the telescope is slightly repositioned between each exposure. Also, the centers of bright stars appear black because they saturate Webb’s detectors, and the telescope’s orientation did not change with exposures to capture the center of different pixels within the camera’s detectors. The overlapping frames of the different exposures can also be seen at the edges and corners of the image.

In this engineering test, the purpose was to lock onto a star and test how well Webb could control his “spin”; literally Webb’s ability to roll to one side like a plane in flight. That test was successful, as well as producing an image that sparks the imagination of scientists who will analyze Webb’s science data, he said. it’s a statement Jane Rigby, Webb 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 that Webb will study in his first year of science operations.Rigby said.

While all four of Webb’s science instruments will ultimately reveal the telescope’s new view of the universe, the fine targeting sensor is the only instrument that will be used on every Webb observation over the course of the mission’s lifetime. FGS has already played a crucial role in Webb’s optics lineup.

Now, during the first real science observations in June and once science operations begin in mid-July, will guide each Webb observation to its target and maintain the necessary precision for Webb to make groundbreaking discoveries about stars, exoplanets, galaxies, and even moving targets within our solar system.