GeminiFocus July 2013 | Page 8

Figure 1. Example clusters detected by ACT. The top shows the ACT clusters, displaying the temperature decrements observed in 148 GHz with blue the coldest and red the hottest. The middle and bottom panels show the optical images of the same clusters, with the ACT maps surrounding them. Three of these four clusters were followed up with Gemini. 8 GeminiFocus July2013