ARLP033 Propagation de K7RA:
August 15, 2003

Propagation Forecast Bulletin 33 ARLP033
From Tad Cook, K7RA
Seattle, WA August 15, 2003
To all radio amateurs

ARLP033 Propagation de K7RA

The average daily sunspot number for the week was about the same this week as last, and daily solar flux was only slightly higher. Solar flux is expected to peak over the next few days, such as it is in this declining phase of the solar cycle. Expect solar flux values around 135 for Saturday, August 16 and then solar flux is expected to gradually decline to below 100 around August 24. Geomagnetic indicators should be unsettled to active today (Friday), but should quiet down over the next week. The predicted planetary A index for Friday through Monday is 20, 15, 10 and 10.

Currently there is just one sunspot group facing earth, and it seems to be growing fast as it moves into optimum position for earth-directed radiation. This presents a wild card for conditions over the next couple of days, since it could be the source of increasing solar wind.

Some editions of last week's bulletin contained a claim that in 57,617 BC Mars was only 34.62 miles from earth, which of course was not the case. So, this error calls for a visit to a news item on the Bad Astronomy web site at

Phil Plait of Sonoma State University in California runs the Bad Astronomy site to help dissuade and debunk some misconceptions that creep into films, television, popular culture and even science textbooks. In an August 13 item he talks about the excitement over Mars being close to earth, and points out that it will be only about 1 percent closer than it was in 1971.

Bruce Irving of Eagle, Idaho was K7ISM many years ago, and he wrote this week asking about some ghosting he saw on his television set after 0200z on Sunday, August 10. He wasn't able to ID the station, but noted that the image of a musical group performing wasn't on any of his other local channels in the Boise area. He asked if this could be skip from a channel 2 station out of his area, and I believe his hunch is correct. He noted that channel 2 is just about the 6-meter ham band, and being the lowest frequency television broadcast channel it is the one most likely to experience long distance propagation. In this case, it was probably some summertime E-layer propagation.

For more information on propagation and an explanation of the numbers used in this bulletin see the Propagation page on the ARRL Web site at .

Sunspot numbers for August 7 through 13 were 121, 111, 107, 112, 118, 114, and 112, with a mean of 113.6. 10.7 cm flux was 137, 132.9, 130, 131.1, 129.2, 123.3, and 130.8, with a mean of 130.6. Estimated planetary A indices were 15, 32, 15, 12, 11, 25, and 17, with a mean of 18.1.