Stokes maps assembled from the GRIS scan of the quiet-Sun region at the disk center. The top panel shows the continuum intensity at 1.56 μm, the Q, U, and V maps are averages over a 0.75 Å wide spectral window using the nominal wavelength of the Fe i 15 648.5 Å line as the central position for Q and U, and as the lower limit for V. The abscissa x is the slit direction, the ordinate y is the scan direction. The blue and red contours mark the Stokes V levels with | V | = 0.002. The symbols mark the location of sample profiles, shown later in Figs. 2, 9, and 10. The contours outline a Stokes V value of ±0.0025.