WISE images of the field around GK Per. Top: wide-angle view (1° × 1°), with blue, green, and red representing the signal in the W2, W3, and W4 filters, respectively. The large interstellar cirrus cloud reported earlier in IRAS observations is shown. Middle: close-up view, with blue, green, and red showing the W1, W2, and W4 images, respectively. In yellow, a bipolar structure is seen near the position of GK Per. Bottom: W2 image of the bipolar structure. Its shape is arbitrarily outlined with the dashed line. The northern edge is not well defined. The field shown (17′.0 × 14′.5) corresponds to the white boxes drawn in the two upper panels. All panels show intensity in linear scale.