VECTOR MAGNETIC-FIELD CHANGES ASSOCIATED WITH X-CLASS FLARES

We present high-resolution transverse and longitudinal magnetic field measurements bracketing five X-class solar flares. We show that the ma gnetic shear, defined as the angular difference between the measured f ield and calculated potential field, actually increases after all of t hese flares. In each case, the shear is shown to increase along a subs tantial portion of the magnetic neutral line. For two of the cases, we have excellent time resolution, on the order of several minutes, and we demonstrate that the shear increase is impulsive. We briefly discus s the theoretical implications of our results.