January 31, 2023

This image from the James Webb Space Telescope features a dense array of galaxies, brilliant stars, and Webb's distinctive six-pointed diffraction spikes. The enormous spiral galaxy at the image's bottom is surrounded by a plethora of smaller, farther-off galaxies, ranging in size from full-fledged spirals to simple luminous blobs. Its designation is LEDA 2046648, and it is located in the constellation Hercules about over a billion light-years away from Earth.

To learn more about the specifics of galaxies' creation, history, and composition, one of Webb's main scientific objectives is to view distant and, thus, old galaxies. As light from older, farther-off galaxies is redshifted towards infrared wavelengths, Webb's strong infrared vision aids the telescope in seeing back in time. Astronomers will be able to better understand how galaxies evolved to develop the structures we see in the cosmos today by contrasting these galactic fossils with contemporary galaxies. Webb will also examine the chemical makeup of thousands of galaxies in an effort to give light on how heavy metals were created and accumulated over the evolution of galaxies.

Astronomers and engineers must first calibrate the telescope's equipment and systems in order to fully realize Webb's potential for galaxy archeology. The starlight received by Webb's main mirror is redirected and focused by a complex network of mirrors and other optical components found in each of Webb's sensors. The commissioning campaign for Webb's Near-InfraRed Imager and Slitless Spectrograph included this exact observation (NIRISS). NIRISS supports concurrent observations with Webb's Near-Infrared Camera in addition to performing science on its own (NIRCam). While NIRISS was monitoring the well-researched white dwarf WD1657+343, NIRCam took this galaxy-filled image. This enables astronomers to characterize the performance of NIRISS and to evaluate and compare data from the two separate devices.

Source - ESA