Figure 3From: Coronal magnetic field and the plasma beta determined from radio and multiple satellite observationsEUV observation from STEREO _A. (a) EUV image of the active region enclosed by the white rectangle in (c) at 304 Å and (b) at 171 Å, observed by AIA. (c) EUV image of the entire solar disc at 171 Å, observed by AIA. (d) High-pass filtered image of (b).Back to article page