Image of the Sun, taken by the SECCHI Extreme Ultraviolet Imager (EUVI)
on the STEREO Ahead observatory on April 18, 2021 at 18:15:45 UT.
The 304 Angstrom bandpass is sensitive to the He II singly ionized state
of helium, at a characteristic temperature of about 80 thousand degrees Kelvin.
This image was produced from the STEREO space weather beacon telemetry.
Because of the high amount of compression used for the space weather beacon,
the image quality is far lower than in the final science product.