Tad Cook, K7RA, Seattle, reports: Sunspots vanished again after appearing on every day, from May 21 through June 4. Average daily sunspot numbers for the May 31 through June 6 reporting week dropped from 26.3 to 12.9.

Average daily solar flux declined from 74.9 to 73.2. Average planetary A index increased from 3.9 to 11.7 while average mid-latitude A index increased from 4.7 to 10.4.

Predicted solar flux is 69 on June 8-10; 70 on June 11-14; 72 on June 15-17; 74 on June 18-23; 72 on June 24-30; 73 and 72 on July 1-2; 70 on July 3-7; 72 on July 8-14; 74 on July 15-20, and 72 on July 21-22.

Predicted planetary A index is 5 on June 8-12; 8 on June 13; 5 on June 14-18; 8 on June 19; 5 on June 20-26; 15, 28, and 18 on June 27-29; 10 on June 30 – July 1; 8 on July 2; 5 on July 3-9; 8 on July 10; 5 on July 11-15; 8 on July 16, and 5 on July 17-22.

The summer solstice in the Northern Hemisphere is less than 2 weeks away — Thursday, June 21, just before ARRL Field Day weekend. Around this time of year, we may see sporadic-E propagation on 10 meters and sometimes on 6 meters. This site is devoted to 10-meter meter sporadic-E.

June 23-24 is Field Day weekend. Predicted solar flux of 74 and 72 looks promising, and the planetary A index prediction of 5 for both days is excellent. Previously, the planetary A index was predicted at 8 for Sunday, and 5 is better.

Our readers write. We received this from Bill Mader, K8TE, president of the Albuquerque DX Association:

“I hope you and Dr. [Tamitha] Skov can educate folks about HF communications on the planet Mars. Although Mars’ atmosphere is approximately 0.6% of Earth’s, there are sufficient atoms to provide an ionosphere according to some scientists.

“However, reading this paper, it’s obvious the authors do not have a lot of experience with the subject, since they state the Mars ionosphere reflects radio signals, rather than refracts them.

“Long ago, I gave a presentation to a middle school class on this very subject. This is before the scientific community knew about Mars’ complicated atmosphere, much less its ionosphere. I suggest satellite communications would be necessary between explorers on Mars’ surface. It may well be you will eventually need to provide HF propagation predictions for hams on Mars!”

Lou, VK5EEE, wrote regarding a recent inquiry on HF beacons:

“Beacons on bands other than 10 meters (28.200 – 28.300 MHz) are discouraged by the IARU, however, there are a few exceptions that have been approved (and many unapproved beacons).

“The most famous and useful is DK0WCY. The German website (with a few pages in English) has a wealth of information, but not something quite basic: The actual power and antenna of the beacon itself. I had to find this out in correspondence. I speak German, so I have also corresponded with DDK9, the German RTTY WX station on 30 meters and obtained information about that station too. To make it easy for hams, I have put together pages (A) (B) that make it easy to find what you need about these.

“If you agree with the aims of the site it would be an honor if you like to join too. But in any event please do make readers aware of this, as 30 meters is a very interesting band for propagation, as you know; I’d call it the Queen Band of HF while I’d call 20 the King. During sunspot minima, the most reliable long-distance DX takes place on 30 meters, in my view, sometimes 24 hours a day, and with less effort of antenna than on 40 meters, and more and longer openings than on 20. Hence, as one of my favorite bands, I devoted a wiki website to it.

“You can find various info on the ‘30m info’ menu on the website, but I think the above one or two links would be of great interest to readers, in partial answer to other useful beacons.

“A very fun beacon is IY4M, just below the 10 meter exclusive beacon band on 28.195 MHz and also on 12 meters. It is extremely hard to find information about this beacon, which is sad, as it is an amazing work.

“You can QSO with the beacon in CW; you give it various commands, such as to speed up, slow down, send this or that info, etc. I used to love having regular QSOs with it from Europe especially during Sporadic E seasons.”

This is from George Ockwell, K7HBN:

“Perhaps it occurred too late in the reporting period, but I’m surprised you didn’t receive any comments on the exceptional conditions during the CQ WPX CW contest, May 26-27. Here in Western Washington, 20 meters was open to somewhere the full 48-hour period. The SFI was 74 to 75 with the A Index 4-5 and the K Index 0-1. Fifteen meters was open to South America with some JA as well. Brief openings also happened on 10 meters.”

The Baker Island DXpedition, which gets under way later this month, has published some propagation guidance.

Other resources from K6TU.

For more information concerning radio propagation, see the ARRL Technical Information Service at. Here is an explanation of the numbers used in this bulletin. An archive of past propagation bulletins is on the ARRL website. More good information and tutorials on propagation are on the website of Carl, K9LA. The ARRL website also offers monthly propagation charts between four US regions and 12 overseas locations. Instructions for starting or ending e-mail distribution of ARRL bulletins.

Sunspot numbers for May 31 – June 6 were 21, 22, 20, 16, 11, 0, and 0, with a mean of 12.9. The 10.7-centimeter flux was 76.8, 74.8, 74.4, 73.6, 70.5, 71.3, and 71.1, with a mean of 73.2. Estimated planetary A indices were 12, 26, 17, 9, 5, 6, and 7, with a mean of 11.7. Estimated mid-latitude A indices were 11, 19, 14, 9, 5, 6, and 9, with a mean of 10.4.