Probability distribution functions (PDFs) of column density for G0.253+0.016, assuming three values of β when scaling the SCUBA 450 μm emission: 1.5, 1.75 and 2.0 (red, black, and blue, respectively). The density-values in the PDF shown for β = 1.5 and 2.0 have been multiplied by factors of 0.87 and 1/0.87, respectively. The PDFs are derived from images with a resolution of 4.3′′ × 2.7′′, or 0.18 × 0.11 pc at a distance of 8.4 kpc. The y-axis shows the number of pixels N_pix per logarithmic bin. The dashed line shows the column density corresponding to the 3σ noise level for the β = 1.75 image, assuming a temperature for the outer regions of the cloud of 30 K.