Spatial variations along the slit of the polarization signals. Panel a: spatial variation at three different wavelengths along a region of the slit of Q/I (left panel), U/I (central panel), and V/I (right panel). The line-center wavelength (gray line) is at λ₀ = 6562.81 Å. The blue wing (blue line) is at λ_b = λ₀ − 0.5 Å and the red wing (red line) is at λ_r = λ₀ + 0.5 Å. The width of the curves indicates the noise level at each spatial pixel. The considered spatial region is shown by the three dashed lines in the panels below. A binning of 2 and 4 pixels along the spatial and spectral dimensions were applied in order to reduce the noise. The spatial resolution of the signals are about 6″. Panel b: spectropolarimetric images. The color scale saturates in black at ±0.2% for Q/I, and U/I and ±0.1% for V/I. The observation was taken at the heliospheric north limb at μ = 0.14. The observation ID is 03.