SDO/AIA 171 Å image and the extrapolated magnetic field. Panel a: full-disk image in 171 Å at 17:20 UT. Panel b: subregion of the SDO/AIA image overlaid with the line-of-sight magnetic field observed by SDO/HMI. The loop path is denoted by the green dashed line and the selected slices are marked by the red dashed lines. Panel c: potential field model overlaid on the AIA 171 Å image. Panel d: side view of the reconstructed loop. The red dashed lines show the slice position on the loop and the direction of the line of sight.