A composite BVR image of the rich cluster A1185 obtained with the CFH12k camera on CHFT (see Andreon et al. 2007) showing the locations of our ACS fields. The field of view is  ~20′ × 16′, corresponding to  ~0.8 Mpc  ×  0.64 Mpc at the distance of A1185. North is up and East is to the left. Our primary ACS field is located just below the brightest cluster galaxy, NGC 3550. A second ACS field located  ~9′ (~350 kpc) to the northeast was used as a control field, as discussed in the text. Several of the brightest galaxies near the ACS field are identified, including the spectacular interacting galaxy pair Arp 105. X-ray contours from Mahdavi et al. (1996) based on Einstein observations are overlaid on the image.