On Rotation of the Solar Corona

We have studied the rotation of the solar corona using the images taken at a 9.4 nm wavelength by the AIA 094 instrument on board the Solar Dynamics Observatory (SDO) satellite. Our analysis implies that the solar corona rotates differentially. It appears that ω, the angular rotation velocity of the solar corona, does not only depend on heliographic latitude but is also a function of time, while the nature of the latter dependence remains unclear. Besides measurement errors, deviations Δω from the mean rotational speed are also caused by proper motion of the observed point source (the tracer) with respect to its surroundings. The spread in ω values at a particular heliographic latitude is a real effect, not caused by measurement errors. Most of the observations carry relative error less than 1 % in ω.