Comparison of moment 0 maps of CH₃CHO (after spectral stacking), SiO, and H¹³CO⁺. The background emission shows 3 mm continuum emission. The white, yellow and red contours are for H¹³CO⁺ emission, SiO, and CH₃CHO, respectively. Their contour levels are [5, 10, 15, 30, 50, 100, 200] × Rms(1, 2, 3). Rms(1), Rms(2) and Rms(3) are shown in the lower right corners, representing the noise values for CH₃CHO, SiO, and H¹³CO⁺, respectively, with units of Kelvin kilometers per second. The beam of continuum emission is placed in the lower left corner of the image.