Magnetic field of the extended AFS. Panel a: single-integration IBIS Stokes–V/I_c map derived from the NIR Ca II line at 17:52:39 UT and panel b: one-hour average of IBIS Stokes–V/I_c maps scaled between V/I_c = ±0.005. Panel c: two-hour average HMI magnetogram clipped between ±150 G, showing the positive (white) and negative (black) magnetic polarities. Panel d: Hα image at 17:52:39 UT with contours of the positive (red) and negative (blue) magnetic field between ±50 G and ±200 G in steps of 50 G, where darker colors indicate stronger magnetic fields. The contours were derived from a single HMI magnetogram at 17:36:00 UT. The labels α, β, and γ indicate three individual arch filaments, which are discussed in the text. A movie associated to this figure is available online.