On Monday around 0500 UTC, SDO pointed toward Regulus, a bright star in Leo. Half of the solar disk was kept on the CCDs and Regulus was to be a rotation indicator, helping us learn the roll angle of SDO around the Sun. Analysis of the data is continuing.
Today at 1920 UTC SDO used its thrusters to dump momentum from its reaction wheels. These wheels keep SDO pointed at the Sun as it orbits the Earth and the high-gain antennas keep turning. All that turning is transfered to the reaction wheels; every so often we have to reduce the wheel spin rates. We used 20 grams of propellant in the maneuver.