Full-disk solar images observed by (a) ALMA at λ = 3 mm and (b) AIA at 1700 Å, on 2015 December 16 centered at 18:32 UT. Details of the region within the rectangles in panels (a) and (b), including the large sunspot of AR12470, are shown in panels (c), recorded by ALMA at 3 mm, and (d), acquired by the HMI in the visible continuum. The red and blue contours in panel (c) indicate the boundaries of the umbra (0.65 of quiet-Sun intensity in the visible continuum) and penumbra (0.9 of quiet-Sun level), respectively. The overlaid color contours in panel (d) indicate the 6300 K (purple), 6900 K (blue), 7500 K (green), 8100 K (orange), and 8700 K (red) brightness temperature levels in the ALMA λ = 3 mm map. The horizontal and vertical axes are the R.A. and decl. offsets, respectively, measured from the disk center position.