The K7RA Solar Update


Geomagnetic conditions are quiet this week, but they may become slightly unsettled over this weekend. The average daily sunspot numbers were down more than 18 points to 74.9, while the average daily solar flux was off less than 4 points to 113.4. Sunspot numbers for April 21-27 were 100, 103, 80, 78, 67, 57 and 39, with a mean of 74.9. The 10.7 cm flux was 113, 114.8, 119.1, 117.2, 112.1, 109.4 and 107.9, with a mean of 113.4. The estimated planetary A indices were 5, 6, 6, 6, 6, 3, and 3 with a mean of 5. The estimated mid-latitude A indices were 4, 3, 4, 6, 2, 1 and 0, with a mean of 2.9.

The predicted solar flux value for today and tomorrow -- April 29-30 -- is 110. Look for 105 on May 1-8, 110 on May 9 and 115 on May 10. The next peak in solar flux is May 11-13, where we are looking for a value of 120. This is actually higher than the flux values over the last month, except for one day -- April 15 -- at 129. Over the last three days, five new sunspot groups emerged. Daily sunspot numbers fell over April 22-27, then rose to 71 on April 28.

The predicted planetary A index for April 29-May 3 is 5, 10, 12, 10 and 8, then 5 on May 4-7, then 8, 15, 15, 7 and 5 on May 8-12. So the two periods in the short term with unsettled to active geomagnetic conditions are May 1 and May 9-10. Geophysical Institute Prague predicts quiet conditions on April 29, unsettled to active on April 30, unsettled May 1-2, quiet to unsettled May 3 and quiet May 4-5.

Angel Santana, WP3GW, of Trujillo Alto, Puerto Rico, writes that the good old days are back for 20 meters: “On World Amateur Radio Day (April 18) at 0304-0630 UTC on 20 meters, I worked 22 stations from Europe and the Pacific, including VK, ZL, FO and NH7 -- all on SSB (and so to get my WARD Award). When working Europe, it looked like it was 3-4 PM local time, something I have not experienced for a long time! Then on this past holiday weekend, I deliberately lost sleep to see how the band was, and it worked the same way: I worked a P29, SV1 and a few more Europeans. I am seeing the same activity on PSK 31, something not seen two months ago. Propagation is really turning on, making 20 meters the 24 hour band again. Plus on Easter Day at 0845, I worked T31A in 40 meters, a new DXCC country for me! Right now at 0850 on April 26 and I am hearing ON4UN working lots of VKs.”

Rol Anders, K3RA, of Elkridge, Maryland (southwest of Baltimore), also likes 20 meters: “On Easter Sunday morning (April 24), there was an excellent long path opening on 12 meters to VR2 and BV from 1200-1230. I worked VR2XMT on phone with my antenna on the long path, then tuned down to CW and heard BU2AQ working Asiatic Russians and Eastern Europeans. He was moderately strong and very solid. I could not hear the stations he was working, but they were all given 599 reports by BU2AQ. I heard no other USA stations calling him for the first 10 minutes or so. A PY was trying, unsuccessfully, but neither he nor I could break the Asia/Europe ‘wall.’ Eventually, several other stations in the US heard him, but we all failed to break through. He started to fade at 1225 in Maryland; however, around 1230, some W8s and W4s got through and he worked a number of them, but by that time, he was very weak in Maryland. Also, I am hearing a return of the longpath on 20 to Southeast Africa around 1200. I haven’t heard that opening for years. Isn’t it great to have 20 meters being an all-day DX band again?”

Rich Dowty, W7EET, of St Paul, Orego,n sent info on an interesting tool called PSK Reporter and its map utility. The map displays stations using digital modes on HF who are tied into the reporting network. The user can click on any of the balloons to display a call sign for a monitor at that location, and then enter that call in a query above the map to display all the stations that it could hear over a specified period of time. You can also click in the balloon on ‘Show all seen by’ link. With the ability to check links on different bands and over different time periods, this is an interesting and useful tool for observing HF propagation. There are some interesting videos showing use of this tool here, here and here.

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.