Compared to the uneventful past few years, sunspot activity was truly remarkable this week. The daily sunspot number for September 16 was 173. We haven't see numbers like this in more than six years, when the sunspot number was 181, way back on July 5, 2005 in Solar Cycle 23. The solar flux reached 150.1 on September 18. Just six months ago it was slightly higher, 153 on March 7 and 155 on March 8, but prior to that the only higher number was 157.3 on August 22, 2005, about 7 weeks after the sunspot number of 181. The average daily sunspot numbers for the past reporting week (Thursday through Wednesday, September 15-21) we up over 45 points from the previous week to 137, and average daily solar flux rose nearly 22 points to 144.

Sunspot numbers for September 15-21 were 167, 173, 138, 144, 128, 101 and 108, with a mean of 137. The 10.7 cm flux was 140.7, 143.1, 144.8, 150.1, 140.9, 144.3 and 144.2, with a mean of 144. The estimated planetary A indices were 5, 2, 32, 5, 3, 6 and 2, with a mean of 7.9. The estimated mid-latitude A indices were 4, 2, 14, 5, 2, 6 and 2 with a mean of 5.

Currently, the solar flux and planetary A index forecast from USAF/NOAA calls for a solar flux of 155, 160, 165 and 170 on September 23-26, 175 on September 27-30, 130 on October 1, and 135 on October 2-5. These flux values through September 30 are quite a bit higher than the values predicted a day earlier in The ARRL Letter. The planetary A index is predicted at 5 on September 23, 15 on September 24-25, 5 and 8 on September 26-27, 5 on September 28-30, 8 on October 1 and 5 on October 2-7. Geophysical Institute Prague sees quiet conditions September 23-25, quiet to unsettled September 26-27 and quiet again on September 28-29.

At 2323, IPS Radio and Space Services in Australia issue a warning of upcoming geomagnetic disturbance on September 24-25 due to a coronal mass ejection.

You can download the latest (October) edition of WorldRadio Online to read this month’s Propagation column from Carl Luetzelschwab, K9LA on pages 30-33. This month’s effort uses ray tracings from the Proplab-Pro software to help explain refraction, absorption and polarization of radio signals.

Today is the fall equinox in the Northern Hemisphere, in fact I am writing these words at the exact time of the equinox, right at 0905 UTC on September 23.

Angel Santana, WP3GW, of Trujillo Alto, Puerto Rico, is excited about all the new solar activity right around the equinox. He wrote: “Almost two weeks ago I did not have much luck in the Worked All Europe SSB contest -- I only had 77 QSOs on 20 and 40 meters. But last Saturday, September 17 at about 1500 ,10 meters exploded with European stations. Did someone say ‘Sunspot numbers over 100,’ and everybody got on the air?I first worked F4EZJ, then OT4A who even asked if there was a contest, due to the fast pace of the contacts. I even worked 5B4AIF and went to 12 meters and worked EA9IB. I then went back to 10 meters and some even answered my call. Later, at 2000, I went to 12 meters and worked another bunch of Europeans. If this is a preview of the upcoming contest period, we’re in for a roll!”

Rob Steenburgh, KA8JBY, says the Space Weather Prediction Center now has a Facebook page. NW7US has a similar Space Weather and Radio Resources page here.

Jeff Hartley, N8II, of Shepherdstown, West Virginia, wrote: “I knew September 16 was probably going to be a good day when 4W6A was the first signal I heard on 21.295 MHz at around 1200; he was not workable, running Europeans I couldn’t hear. Twenty meters sounded fair, logging BP100 (Taiwan) and BA8AG. Then a quick check of 15 meters at 1245 showed 4W6A up to about S-4-5 and looking for ‘North America only’; after several tries, he was in the log, he was busy. By 1300, European signals were loud on 15, and 12 meters was opening up to Europe. I logged 4K9W, OM5DP and OE3GCU on 12 meters, then checked 10 meters at 1314 and found YL2SM S7 running 4/4 Yagis and a KW; he was getting very few CQ answers. At 1416, I found E21EJC in Thailand signing with a station on 28.005 MHz CW. Kob was about S-5-6 and gave me a ‘599, very loud’ report -- what a surprise! Eventually at 1418, I had a nice CW run of stations on 10 meters as far as the Ukraine and as far north as Poland and Hungary and west as The Netherlands. I found good signals on 12 meters from RA3CQ and SK2AT. Starting at 1457, I was able to run Europeans on 10 meter phone, with some having S9+ signals as far west as EI3JS, north to DJ8CG and east to 9A1HDE. After a long break, I returned to some of the best late-day 12 meter conditions to Europe I can ever remember. Between 1856 and 1933, I ran off about 25 European SSB QSOs, including SM5FQQ and six Polish stations. Everybody was loud; I never got down to the weak ones until right at the end. Then, a check of 10 meters yielded a SSB QSO with EC1KR at 1935 who was S-7.

“On Saturday September 17, the Scandinavian Activity CW Contest started at 1200, which is only about an hour after sunrise. By 1220 when I fired up, OH9W in very northern Finland had a good signal on 15 meters. Finland was the best place to be in almost all of Europe for a while; Norwegians were very weak and European stations calling the Finns were much weaker than they were, pretty ideal conditions for the contest! By 1330, Swedish and Norwegian stations were much better, and 10 meters was open over a scatter path beaming 90-120 degrees over Southern Africa, which persisted until past 1500. I managed to make 15 Scandinavian scatter path QSOs on 10 meters; the loudest were good copy about S-3-4, but most were right near the noise level. LN3Z and OH3MEP were the loudest. Twenty meters at 1500 was not very good and the K index was rising; it was 5 as of 2000! Forty and 80 meters were horrible to Scandinavia at 0130, but improved quite a bit by 0330. There were some loud Northern Scandinavians on 20 at 0130, and others reported 15 meters open as late as 2300.”

Jimmy Mahuron, K9JWJ, of Salem, Indiana, and several other readers sent in a link to an article from NASA Science News titled “The Secret Life of Solar Flares.”

Jon Pollock, K0ZN, of De Soto, Kansas writes: “I was on 17 meters this evening (September 18) and found signals were extremely strong to both east and west late into the evening. I worked WA2MDF at about 9:30 PM CDT and he was running well over S-9 with 100 W and a 170 feet end-fed long wire. About 30 minutes later, I worked K6GVG in San Diego at about 10:15 CDT. He was peaking 20 dB over S-9 at times! These are some of the strongest signals I have heard in a long time on 17 meters at this hour of the night -- and from both coasts nearly simultaneously. The band was very quiet (low noise), which usually means very long skip. I also heard some weak Japanese and Australian stations in the CW band. My antenna is nothing fancy: a 128 foot center-fed Zepp at 40 feet. Conditions tonight reminded me of the ‘good old days’, the previous sunspot peaks.”

Fred Honnold, KH7Y, of Ocean View, Hawaii (the south-southwest corner of the Big Island) wrote on September 18: “I wanted to let you know we have been having excellent TEP (Trans-Equatorial) openings on 6 meters the last two weeks. In the last week, I worked FK8CP, E51USA, A35CT, VR2XMT, BD7OH, BA7s and many Australian, Japanese and Philippine stations. During last night’s opening, TV from China on 49.749 MHz was 40 dB over S-9 at times. The 6 meter band was full of sync buzz for about three hours -- a very exciting evening! Seems the openings start about 0600 and can last until 1000 just about every night here in Hawaii.”

Reg Beck, VE7IG, of Williams Lake, British Columbia (at 52.13 degrees north latitude), wrote: “I was up in the middle of the night and checked 12 meters around 0930 on September 17 here in VE7. It was wide open over the North Pole into Europe and Central Asia. I logged a lot of Europeans and some Asians in Zone 17. I couldn’t get through the big pileup to JT1DX, but he was loud at times. The band was up and down with very loud signals suddenly dropping down, then coming up with flutter, then clearing, then flutter again, and then weak. The opening lasted past 1000 then went out.”

Julio Medina, NP3CW, of San Juan, Puerto Rico, wrote: “Today (September 16) we had a good opening to Europe with signals from 559 to 579 on 28.050 MHz from 1445-1737. Stations worked: OH1ND, IK1RGK, SP1KQR, DF9KF, DL1KUR, DL7UAG, DL7HC, OK1DKO, 4X4FW, DL6DCD, DL1DAW, DJ3EF, DL5MGH, DJ2RG, DL/KJ4HFR, DJ1YU, G0TBD, DF8BY, DL6HRW, HB9US, F8GFA, F8PEU, DH8IAB, EI7CC, F6GVC, EA4RU/M, F5DM, M0BAU, G4GGZ, OK1BN, GU4HUY, M0CYR and G4EVR.”

All times listed are UTC, unless otherwise noted.

Amateur solar observer Tad Cook, K7RA, of Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here and here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.