Observation scheme. We systematically scanned the quiet Sun at up to eleven heliocentric positions from the disk center (DC, μ = 1.0) toward μ = 0.3, or μ = 0.2, close to the solar limb. The observations were performed along the meridional (N-S) and equatorial (E-W) radians: north (blue, circle), south (green, rectangle), east (orange, diamond), west (red, triangle). The black ellipses indicate the spatially integrated area (not to scale). Throughout this work, we maintain the color code (blue to red) of the heliocentric position along the axes, as well as the colors and symbols for the respective axes.