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The K7RA Solar Update


Sunspot 998 emerged this week, another old Solar Cycle 23 sunspot near the Sun's equator. Daily sunspot numbers for June 10-12 were 14, 11 and 13. Last Sunday, June 8, had the lowest 10.7 cm solar flux value I've ever seen -- 64.9 -- at the observatory in Penticton. The noon reading is the official daily sunspot number; the value observed that morning at 1700 UTC was actually a tiny bit lower at 64.8. The only value this low I have in my records was almost a dozen years ago near the last solar minimum, July 19, 1996.

The 10.7 cm solar flux is a measurement of energy at 2.8 GHz gathered by an antenna in British Columbia. The facility is the Dominion Radio Astrophysical Observatory (DRAO) that sits 168 miles northeast of my Seattle location at approximately 49.322 degrees north latitude, 119.621 degrees west longitude.

The solar flux value is a general indicator of solar activity, but not as useful as sunspot numbers for predicting propagation. You can see all three daily flux readings here. Although this just accesses a text file on a server using file transfer protocol, the URL also works in a Web browser. The flux value you want is in the fluxobsflux column. The fluxdate column shows the date the value was observed -- when you see 20080613, it means June 13, 2008. The fluxtime column shows the time of the observation; 170000 means 1700 UTC. The official daily solar flux is measured at 2000 UTC, or 200000 in fluxtime.

Geophysical Institute Prague expects quiet conditions for June 13, quiet to unsettled June 14, unsettled June 15-18 and quiet to unsettled June 19. Sunspot numbers for June 5-11 were 0, 0, 0, 0, 0, 14 and 11 with a mean of 3.6. The 10.7 cm flux was 66.4, 65.9, 65.6, 64.9, 66, 66.2, and 65.7 with a mean of 65.8. Estimated planetary A indices were 2, 8, 12, 7, 5, 4 and 4 with a mean of 6. Estimated mid-latitude A indices were 3, 7, 10, 5, 2, 1 and 3, with a mean of 4.4. NASA predicts more of the same quiet conditions, with slight possible unsettled conditions on June 18, with a planetary A index of 12. They expect solar flux to stay below 70 until mid-July.

Paul Kelly, NN5G, of Oklahoma City, Oklahoma, asked about expected stateside coverage for a net on 20 meters at 2000 UTC, with net control in the middle of the contiguous 48 states. He is trying to use charts to determine a better time for the net. I suggested he use W6ELprop that was described in the May 9, 2008 edition of the Solar Report. This way he can test over any path and account for seasonal variations in addition to time-of-day factors. Propagation prediction software isn't perfect, but can give you good odds on what is likely to work, given the time of day, the particular path, the band used, the season and an average of recent sunspot activity or the predicted smoothed sunspot number for the month.

Testing the path on 20 meters from my home to the center of the country, 2000 UTC seems a good time of day. Same thing with Boston and the few other places I examined. It gets tougher if the path is shorter and other choices such as 40 meters, or even 30 meters (since his net uses a digital mode), is a good choice.

Not much sunspot activity of note, but this is the sporadic-E season, so some interesting work has been popping up on 6 and 10 meters.

This is late, but two weeks ago this bulletin reported from Julio Medina, NP3CW, in Puerto Rico and his 6 meter fun on May 22-23. Subsequent to that, he had much success on May 26-29. On May 26, he reported a nice opening to Europe, mostly to Spain, Portugal and the Canary Islands. On May 27 he worked F6FHP, F1PUX in JN26, DK1MAX in JN58, SP6GWB in JO80, PA2M in JO21, and PA0O and 9Y4D in FK90. The following day he worked G4DEZ in JO26, CN8KD in IM63 (Morocco), and VE1YX in FN74. On May 29 it was on to FM5LD in on CW, K5RQ, K4SN in EL96, AA4ET in EL96, W4ZE, 8P9TS in GK03, and 9Y4D.

Vince Varnas, W7FA, of Aloha, Oregon, sent a very encouraging 6 meter report: "There was a GREAT (for the bottom of the sunspot cycle) 6 meter sporadic-E opening to Japan on June 10 from Portland, Oregon (CN-85). The band was open from about 2245-2330 UTC. I worked 16 stations in six JA call areas on SSB during this time with signals averaging about S-5. It wasn't as good as the F2 openings in years gone by. I was still in great demand with a pile up on me of about 4-5 JA stations calling for 45 minutes on 50.110 MHz". Vince also worked two Puerto Rican stations, KP4EIT and WP4G, on 6 meters on June 9 around 1850 UTC.

Johnny Kiesel, KE7V of Sequim, Washington, gives a similar 6 meter report for June 10. He worked 38 Japanese stations in all 10 districts, beginning at 2225 UTC with JE1BMJ and ending at 2327 UTC. That is about one JA every 98 seconds. He reported that JE1BMJ over the past week worked W4, 5, 7, 8, 9 and 0 call areas on 6 meters, and may have set a sporadic-E distance record -- 13,000 km -- to HI3TEJ in the Dominican Republic on June 11.

There is a nice one-page article on 6 --meter sporadic-E propagation in the July 2008 issue of QST, titled "Summer E-skip and the Magic Band." Check it out on page 55. Written by Gene Zimmerman, W3ZZ, it has many good suggestions for summertime fun on 6 meters, including a good outline of the fundamentals. I'm going to read it again right now before I write another word about E-layer propagation.

The summer equinox is just one week away. We hope for more frequent and larger sunspots, but most are grateful for any darkness shadowing the solar disc. More sporadic-E propagation would be nice this weekend during the ARRL June VHF QSO Party. The key to scoring is to work many grid squares, which are multipliers.

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 in The ARRL Letter. Check 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.



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