The following images show center-of-gravity variations averaged over pixels with an intensity considered "significant". The scan was taken in Mg X.
The following images demonstrate the effect of subtracting these average variations from the initially determined lineshifts: The first example is again Mg X (initial data, detector effect correction, temporal effect correction), the second example is the same for N V.
Mg 10
N V
While the final results still cannot be called "calibrated" in a narrow sense, at least some bias is eliminated and the images may give a better overview of what is really going on. For example, in the final N V image, the faint prominence at the very north edge shows different velocities for the upper and lower part of the "tube", hinting to a rotational movement.
IED, 13.Oct.97