SDO is GO: By now I am sure people are aware that something continues to move along the orbit of Comet ISON in the LASCO observations. It is being discussed whether it is debris from Comet ISON or a remnant. In either case we should try to understand why we didn't see that debris or remnant as it went through perihelion yesterday. When SDO looks for a comet it does not see the dust and ion tails seen in a comet far from the Sun. We see oxygen ions, oxygen atoms with some electrons stripped off, glowing when they are hit by the hot electrons in the corona. The AIA telescopes normally look at iron ions, but the enormous amount of oxygen that comes off a comet allows that element to emit brighter for a while after the comet passes. The images we showed yesterday were our best guesses for which AIA passbands would show bright emissions from Comet ISON as it flew past the Sun. They are the passbands that showed Comet Lovejoy in December 2011 and the earlier comet in June 2011. All four passbands would show emission from O IV, O V, or O VI, oxygen atoms with 3, 4, ...