An X1.9 Class Solar Flare and its Aftermath - January 9, 2023

  • Released Friday, February 10, 2023
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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.

Here, Active Region 13164 (near the lower left limb of the solar disk) fires off a hefty X-class flare (X1.9). (Solar Flares: What does it take to be X-class?). The region continues some active evolution with loops and filaments more visible in the 171A and 304A filters. Smaller M-Class flares erupt later in this sequence, an M 5.1 at the upper left limb and an M 2.6 in the lower right center. The point-spread function correction (PSF) has been applied to all the imagery on this page.

The X1.9 flare event of January 9, 2023 as seen in the SDO AIA 131 angstrom filter. Two smaller M-class flares occur at later times on other regions on the solar disk. The dark region around the central 'X' marking the flare is an artifact of the PSF correction. 'Flickering' in the images around the flare are created due to the 'flare mode' images which have a shorter exposure. Normalizing the solar disk to the same brightness in these frames enhances the background noise off the solar disk.

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.
Time slates for the multiple movies above, for custom compositing. Make sure to match the event and frame tag for the SDO frames you are using.

Time slates for the multiple movies above, for custom compositing. Make sure to match the event and frame tag for the SDO frames you are using.


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Release date

This page was originally published on Friday, February 10, 2023.
This page was last updated on Wednesday, May 3, 2023 at 11:43 AM EDT.


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