‰ Now 18 WPM transition file follows ‰


So far this month weve observed 9 days in a row with 0 sunspots, and
all of our reporting week for this bulletin, April 5 through 11,
falls within this string of inactive solar days. As noted in last
weeks bulletin, comparing that weeks average sunspot number, 12R9,
to this weeks doesnt mean much when activity is so low at the bottom
of this sunspot cycle. Based on predicted smoothed sunspot numbers,
if this month and the next are truly the solar minimum, we should
probably see several weeks in a row with no sunspots.  Those hoping
for more activity and a return to worldwide propagation on 10 and 15
meters should be cheered by this, because recent observation shows
the rise of any solar cycle is faster than its decline, and most
importantly, the decline of the previous cycle.  Around the last
solar minimum, between Cycles 22 and 23, Sun watchers observed
several long strings of days showing no sunspots.  For instance,
from February 10 to March 5, 1997, the average sunspot number was
2R1, and there were 20 days during that period with no sunspots.
Prior to that, another long stretch of inactivity occurred in the
Fall of 1996.  The average daily sunspot number was 1R7 from
September 5 to November 8, when 57 of 65 days the Sun showed no
spots. The longest continuous stretch with no sunspots at all in
that period was 38 days, following September 12, when a single
sunspot was visible and ending October 21, when another sunspot
appeared. Both those days had an official sunspot number of 11, and
each time, the single sunspot was only visible for a single day.
This period was preceded and followed by three days of no sunspots,
and October 29 through November 8, 1996, also had zero sunspots,
followed by December 24 through January 3, 1997.  Remember that an
average sunspot number of 1 or 2 doesnt correspond to one or two
sunspots. Because of the peculiar manner in which sunspot numbers
are derived, the minimum non zero sunspot number on any day is 11.
This is because the number of sunspot groups is multiplied by ten,
and the resulting number is added to the total number of visible
spots. So two spots in one group is 12, three spots is 13, but three
spots in two groups yields a sunspot number of 23.  Sunspot numbers
were 0, 0, 0, 0, 0, 0 and 0 with a mean of 0. 10R7 cm flux was 70R9,
71, 71R2, 71R1, 69R9, 69R4, and 69R1, with a mean of 70R4. Estimated
planetary A indices were 4, 4, 3, 3, 9, 7 and 4 with a mean of 4R9.
Estimated mid latitude A indices were 3, 2, 2, 2, 8, 6 and 3, with a
mean of 3R7‚

‰ End of 18 WPM transition file ‰