Solar X-Flare - April 20, 2022 (X2.2 class)

Released Thursday, September 22, 2022
Updated Tuesday, January 10, 2023 at 7:38AM

ID: 4999

- Visualizations by:
- Tom Bridgman
- Produced by:
- Scott Wiessinger
View full credits

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.

An X2.2 class solar flare erupts on the southern limb of the Sun in the early hours of April 20, 2022. This flare is very close to the lower right of the solar limb and most visible in the 131 Angstrom filter (teal color table). Solar flares are classified by the amount of energy released (Solar Flares: What Does It Take to Be X-Class?)

The solar flare as seen in the SDO AIA 131 Angstrom filter. Correction has been applied for the instrument point-spread-function (PSF).

The solar flare as seen in the SDO AIA 171 Angstrom filter. Correction has been applied for the instrument point-spread-function (PSF).

The solar flare as seen in the SDO AIA 304 Angstrom filter. Correction has been applied for the instrument point-spread-function (PSF).

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.