IRIS Mg II h₃ full-disk mosaic and AIA full-disk images showing the DH surrounding AR NOAA 12706 in the northern hemisphere on April 22, 2018. The three images are center-to-limb corrected. Left panel: the three fibrillar DH contours are shown in shades of green and the outer AR-core edge is shown in red. Middle and right panels: AIA 171 and 193 Å filtergrams, respectively, taken at 19:24 UT. The three coronal DH contours are shown in shades of violet in the AIA 171 Å image, while the QS box and the three southern CH contours are shown in white and in shades of blue, respectively, in the AIA 193 Å image, as described in Sect. 3. The contours are obtained through intensity thresholds from the non center-to-limb corrected images.