By early November, AR 486 had rotated close to
the west limb as viewed from Earth and was about
to disappear from view onto the far side of the Sun.
On November 4, AR 486 was located right on the
limb, at 89° west of central meridian longitude, and
the visible disk was devoid of any significant active
regions (Fig. 7). Just as solar observers were about to
breathe a sigh of relief, and activity appeared ready to
return to normal levels, AR 486 produced the largest
X-ray flare ever recorded, at 19:31 UTC on November
4. The flare saturated the GOES X-ray detector, and
later analysis yielded a peak X-ray flux at the X28
level (peak flux of 2.8 × 10–3 W/m2
). Intense radio
bursts across a broad range of frequencies were associated
with the X28 flare. A category R5 (extreme)
radio blackout resulted at Earth shortly after the flare.
LASCO recorded an extremely fast CME, moving
outward at a speed of 2,657 km/s. The mass of this
CME was about 1.5 × 1013 kg, yielding a kinetic
energy of 5.3 × 1025 J.