(Top) EIT image in 171 Å at 13:00 UT on February 27, 1998, with two MDI isocontours overlaid (± 100 G) shown with continuous lines (positive: white line, negative: black line). The MDI magnetogram was taken at 12:48 UT. (Bottom) The same EIT image with more isocontours (± 100, 500 G) shown with gray lines and computed field lines superimposed (black continuous lines). Both axes are measured in Mm in the local solar frame.