Impressive solar filament eruption - January 20, 2023

Solar Dynamics Observatory (SDO) operates in a geosynchronous orbit around Earth to obtain a continuous view of the Sun. The particular instrument in this visualization records imagery in the ultraviolet portion of the spectrum at wavelengths normally absorbed by Earth's atmosphere - so we need to observe them from space.

A large solar filament hovers above the solar surface (lower right) for several hours before eventually launching into space.

What is the PSF (Point Spread-Function)?

Many telescopes, especially reflecting telescopes such as the ones used on SDO (Wikipedia), have internal structures that support various optical components. These components can result in incoming light being scattered to other parts of the image. This can appear in the image as a faint haze, brightening dark areas and dimming bright areas. The point-spread function (Wikipedia) is a measure of how light that would normally be received by a single camera pixel, gets scattered onto other pixels. This is often seen as the "spikes" seen in images of bright stars. For SDO, it manifests as a double-X shape centered over a bright flare (see Sun Emits Third Solar Flare in Two Days). The effect of this scattered light can be computed, and removed, by a process called deconvolution (Wikipedia). This is often a very compute-intensive process which can be sped up by using a computers graphics-processing unit (GPU) for the computation.