Solar activity spiked up again this week, with average daily sunspot numbers rising from 73 to 120.9.  Likewise, average daily solar flux tracked upward from 106.7 to 122.7. Nice to have increased solar activity coincide with the autumnal equinox, right when HF hams are more likely to be active.

Predicted solar flux is 120 on October 2, 115 and 105 on October 3-4, 100 on October 5-8, 115 on October 9-10, 110 on October 11-12, then 115, 120 and 125 on October 13-15, 130 on October 16-18, 125 on October 19, 120 on October 20-24, then 130, 125, 120 and 115 on October 25-28, 110 on October 29 through November 1, 115 on November 2-6 and 110 on November 7-8.

Predicted planetary A index is 22, 24, 33 and 23 on October 2-5, then 14, 8, 5 and 10 on October 6-9, 8 on October 10-14, then 12, 10 and 12 on October 15-17, 8 on October 18-24, 7 on October 25-27, then 15, 10, 7 and 15 on October 28-31, and 12, 8, 12, 18 and 10 on November 1-5, and 8 on November 6-11.

The Australian Space Forecast Centre sent a geomagnetic warning at 2330 UTC on October 1. They expect increased geomagnetic activity from October 2-4 due to a high speed wind stream from a coronal hole. We should see active geomagnetic conditions on October 2-3, and active to minor storm on October 4.

Petr Kolman, OK1MGW, of the Czech Propagation Interest Group sees the geomagnetic field as quiet to active October 2-3, quiet to unsettled October 4-6, active to disturbed October 7-8, quiet to unsettled October 9-10, quiet to active October 11-14, quiet to unsettled October 15, quiet to active October 16-17, mostly quiet on October 18-20,

The monthly averages of daily sunspot numbers for May through September were 83, 77.4, 68.5, 61.7, and 72.5.  The three month moving averages of daily sunspot numbers centered on January through August were 98.2, 78.1, 68.2, 72.4, 77.7, 76.3, 69.1 and 67.5. A three month moving average centered on August incorporates a sum of all daily sunspot numbers from July 1 through September 30, divided by 92, the number of days. A three month moving average centered on July incorporates all data from June 1 through August 31.


Rol, K3RA, from Elkridge, Maryland wrote on October 1:

“I saw so many signals in the RTTY segment on Sunday for the CQ WW contest that I couldn’t resist getting into the competition for a while. In less than five hours of on time between 1422Z and 1950Z I worked over 300 stations, virtually all in Europe, with great signals.

“I did get called by HS5NMF (Thailand) at 1553z, and before that a couple of VU made it particularly exciting.

“Encouraged by the RTTY fun, on Monday morning I got on 20 meters and at 1245Z found VR2CD, then JT1AA/5, among the EU and near Asians.

“Went to 17 meters and worked a few really strong JAs. Then after working a lot of European stations, at 1420Z I went to 12 meters to work SU1IG (Egypt) and saw the band was wide open.

“I was on only briefly on Tuesday, but I did work A93JA (Bahrain) on 12 meters at 1309z. On Wednesday I went right to 12 meters at 1230z and ran EU with a few Middle Eastern and Western Asian stations thrown in until noon (local time), when I went off the air with the band still open.

“DF2OB, with his huge Optibeam farm, was incredibly strong at 1315Z, and I asked him to try 10 meters, which he did, and there was not a peep! Amazing what such a relatively small difference in frequency can do!

“Thursday morning I got on 12 meters at 1347Z and worked 4K9W with good signals, and then worked a few more Europeans before going to 15 meters to check for signals over the pole. I found YC1CZZ with his friends YB8TM and YC1QL on SSB, all three with good signals.

“I tried a CQ to Asia/OC over the pole, with no luck, but lots of Europeans were calling despite my directional CQ, so I ended up running a couple of hundred European stations on 15 meters before quitting at 1655Z with the band still open. I understand from a couple of the EU stations that N4BP was heard on 10 working EU during the morning. I wonder what tomorrow will bring?”

Check out this article on sunspot formation, at http://bit.ly/1QPnXCP .


For more information concerning radio propagation, see the ARRL Technical Information Service at http://arrl.org/propagation-of-rf-signals. For an explanation of the numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation. More good information and tutorials on propagation are at http://k9la.us/.

My own archives of the NOAA/USAF daily 45 day forecast for solar flux and planetary A index are in downloadable spreadsheet format at http://bit.ly/1VOqf9B and http://bit.ly/1DcpaC5.

Click on “Download this file” to download the archive, and ignore the security warning about file format. Pop-up blockers may suppress the download.

Monthly propagation charts between four USA regions and twelve overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.

Sunspot numbers for September 24 through 30 were 86, 145, 138, 154, 120, 125, and 78, with a mean of 120.9. 10.7 cm flux was 106.8, 119.8, 120.2, 127.5, 124, 129.2, and 131.1, with a mean of 122.7. Estimated planetary A indices were 8, 7, 4, 4, 4, 6, and 3, with a mean of 5.1. Estimated mid-latitude A indices were 8, 6, 4, 4, 5, 5, and 2, with a mean of 4.9.