‰ Now 18 WPM transition file follows ‰
This is a follow up to last Wednesdays pre Thanksgiving Propagation
Forecast Bulletin ARLP048. It was a little early to provide the
complete Thursday through Wednesday sunspot, solar flux, and A index
that normally appears in Fridays bulletin, so we are including it
here at the bottom of this bulletin. The next bulletin will be out
four days from now. Our exciting period of nearly daily sunspot
activity ended with the first spotless day on November 23, and the
Sun has been blank since then. A look at the STEREO image shows a
bright active area perhaps five days over the eastern horizon, but
we dont know if that will give us sunspots or not. As the two
STEREO craft move further from earth, the visual gap on the Suns far
side is gradually closing, and we look forward to the time in 2011
when all of the Sun will be visible from STEREO and earth.
Currently the gap is about 14R3 percent. You can calculate the
approximate percentage of the Sun in that dark spot by using the
Where is STEREO? link on the STEREO home page. Check the Separation
angle A with B stat at the bottom, subtract that number from 180,
divide the result by 360, then multiple that result by 100 to get a
percentage figure. You can check future dates by clicking on the
STEREO Orbit Tool link as well. When you check February 1, 2010 at
0000 UTC it yields a separation angle of 135R197 degrees.
Subtracted from 180 degrees, this yields 44R803, divide that by 360,
then multiply by 100, and you get approximately 12R45 percent
remaining on the dark side. October 1, 2010 yields 5R58 percent,
and January 1, 2011 just 1R26 percent in the dark. Check the
arithmetic. WorldRadio Online posts a new issue on the twentieth of
each month, and each has a column on propagation by Carl
Luetzelschwab, K9LA. You can download it and read Carls article on
The Impact of Deep Solar Minimum on 160m Propagation. Carls column
begins on page 28 of the current December issue. The January 2010
issue should appear online on December 20. For more information
concerning radio propagation, see the ARRL Technical Information
Service web page. For a detailed explanation of the numbers used in
this bulletin, see the k9la prop link off the TIS web page. An
archive of past propagation bulletins is also available. Monthly
propagation charts between four USA regions and twelve overseas
locations are at the qst/propcharts link off the ARRL web page.
Instructions for starting or ending email distribution of this
bulletin can be found on the W1AW web site. The multiple websites
mentioned in this bulletin can be found in teleprinter and packet
versions of Propagation Forecast Bulletin ARLP049. Sunspot numbers
were 30, 31, 14, 13, 0, 0, and 0 with a mean of 12R6. 10R7 cm flux
was 76R7, 76R2, 75R8, 76R3, 75R7, 74R7, and 74R2 with a mean of
75R7. Estimated planetary A indices were 2, 1, 8, 4, 0, 6 and 5
with a mean of 3R7. Estimated mid latitude A indices were 0, 2, 6,
2, 0, 3 and 4 with a mean of 2R4‚
‰ End of 18 WPM transition file ‰