At the end of October 2003 three extremly big and extremly active sunspots
appeared almost 2 years after the solar max. The biggest sunspot of solar cycle
23, called NOAA10486 launched 2
strong coronal mass ejections (CME) together with X17 and X10 x-ray flares
from the center of the solar disc on October 28th and 29th. These CME's started
with velocities of more than 2000km/s near the sun and reached earth after a
traveltime of only 19 hours.
After the sunspot 10486 had moved to the suns limb on November 04th, it exploded
in the strongest
x-ray flare on record. This x-ray flare saturated the detectors onboard
the GOES satellite for 11 minutes and was later rated as an X45 flare.
The arrival of the shockfront from the first mass ejection from the center of
the solar disc led to an immediate start of a G5 (scale G1 to G5) geomagnetic
storm in the early morning hours of October 29th. Even in Germany the deviation
of the magnetic field was measured on the order of 1000nT, which is normally
common for regions near the arctic circle. In the evening of that day there
were many sightings of bright auroral activity from northern and northwestern
Germany. In all other regions of Germany clouds prevented a view to the sky.
The arrival of the second shockfront in the early evening hours of October 30th
was hard to discern because the solar wind speed was still very high (>1200km/s)
and the interplanetary magnetic field was also still very strong. But immediately
after the arrival, the ongoing geomagnetic storm regained strength and again
reached the G5 mark. Overall the event was one of the strongest and longest
geomagnetic storm ever observed.
The auroral display during the night from 30th to 31st of October was seen almost
everywhere in Germany due to a cloud-free zone that moved from the southwest
to the northeast.
I did my own observations in a hillsite somewhere to the west of Mainz. The
auroral display was the brightest one I have seen so far. It was so bright that
it outshone even bright stars (1mag).
The aurora during the night of October 30/31 was permanently visible. There
were 3 stronger substorms:
1st phase: 19:51 - 20:05 UTC
2nd phase: 21:12 - 21:28 UTC (brightest substorm)
3rd phase: 00:23 - 00:39 UTC (substorm with the most southerly extension, not
observed by myself)
Here are my pictures, taken near Wolfsheim (to the west of Mainz) (49.88°N, 8.04°E).
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