Propagation de K7RA

Average daily sunspot numbers this week were down nearly 31 points to 13.4, and average daily solar flux declined over 8 points to 77.

Sunday through Thursday of this week, the sunspot number was 11 on all five days. Sunspot activity should remain low.

This week a coronal wind stream caused a geomagnetic disturbance centered on September 18. A week ago, on Friday, September 15, geomagnetic conditions were very stable.

The mid-latitude K index throughout the day was zero on all eight readings, and so the mid-latitude A index was also zero. Even the high latitude college A index near Fairbanks, Alaska was zero that day.

Due to a recurring coronal hole, we may see a rise in geomagnetic activity this weekend, with the planetary A index predicted at a low of 5 on Friday, then rising to 20 on Saturday, September 23.

Today a group of satellites should be launched that will give
3-dimensional views of solar flares. The plan is to view flares
from two satellites, spaced far enough apart to give stereo vision.

Jerry Reimer sent a link to an article about this in Britain's
Sunday Times. Read it at http://tinyurl.com/rejj8.

Yvone Dubois, KE7HTQ of Phoenix asks, ''Where can I find propagation charts old style, like they used to be published in QST for decades?''

The charts have moved from the magazine to the web. Find them at http://www.arrl.org/qst/propcharts/

If you would like to make a comment or have a tip for our readers, email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL Technical Information Service at
http://www.arrl.org/tis/info/propagation.html. For a detailed
explanation of the numbers used in this bulletin, see
http://www.arrl.org/tis/info/k9la-prop.html.

An archive of past propagation bulletins is at http://www.arrl.org/w1aw/prop/ .

Sunspot numbers for September 14 through 20 were 25, 12, 13, 11, 11, 11 and 11 with a mean of 13.4. 10.7 cm flux was 82.8, 80.1, 79.2, 78, 74.4, 73.4, and 70.9, with a mean of 77. Estimated planetary A indices were 6, 3, 3, 16, 24, 12 and 5 with a mean of 9.9. Estimated mid-latitude A indices were 4, 0, 1, 9, 16, 8 and 3, with a mean of 5.9.

Source: The American Radio Relay League