No sunspots were observed since June 15, when the daily sunspot number was 11. This does not mean there were 11 sunspots seen, but instead it means that one sunspot group was observed containing one sunspot. The sunspot number is derived by assigning 10 points for each sunspot group, and one point for each sunspot. So, 11 is the minimum non-zero sunspot number.
On June 8, the daily sunspot number was 17, indicating 7 sunspots in one group.
If those seven sunspots had been in two groups, the sunspot number would be reported as 27.
Last week’s bulletin ARLP025 reported average daily sunspot number of 7.9, and of course with no sunspots, this week that number dropped to zero.
Average daily solar flux declined from 70 to 67.7.
The sun has gone quiet again, as Spaceweather.com reported this week.
Geomagnetic indicators are still quiet, but the average planetary A index rose from 3.9 to 4.6 and the average middle latitude A index rose from 4.9 to 5.6. These values are insignificant.
Predicted solar flux for the next 45 days is 69 on June 26 through July 3, 70 on July 4-12, 68 on July 13-25, 70 on July 26 through August 8 and 68 on August 9.
Predicted planetary A index is 5 on June 26, 8 on June 27, 5 on June 28 through July 3, then 8, 5, 8 and 8 on July 4-7, 5 on July 8-30, then 8, 5, 8 and 8 again on July 31 through August 3, and 5 on August 4-9.
Geomagnetic activity forecast for the period June 26 until July 22, 2020 from F.K. Janda, OK1HH.
Geomagnetic field will be
quiet on: June 28, 30, July 1, (2,) 3, (6,) 9-11, 14-15, 18-20, 22
quiet to unsettled on: June 27, 29, July 4, 8, 12-13, 17, 21
quiet to active on: (June 26, July 5, 7, 16)
unsettled to active: nothing predicted
active to disturbed: nothing predicted
Solar wind will intensify on: June 26-27, (28-30,) July (4,) 5-8,
(9-10, 16-18, 22)
Parenthesis means lower probability of activity enhancement.
The predictability of changes remains lower as there are very few indications.
A new video from Dr Tamitha Skov, WX6SWW: https://youtu.be/0bs3cHgBrVw
Phys.org has an article on inner workings of our Sun: https://phys.org/news/2020-06-motions-sun-reveal-sunspot.html
Here is a highly technical article on sunspots from Astronomy and Astrophysics: https://www.aanda.org/articles/aa/pdf/forth/aa37739-20.pdf
This weekend is ARRL Field Day, the most popular annual operating event. The 2020 Field Day has a rule waiver for this year allowing Class D stations operating from home and on commercial power to work each other. In the past they could only work all the other classes of stations.
Some operators don’t realize that Field Day has only minimal logging requirements, just submit a list or dupe sheet for each band/mode showing the calls of the stations worked, and a summary sheet. There is no requirement to log the time of each contact, or even record the section or any report from stations you work. See the rules at: http://www.arrl.org/files/file/Field-Day/2020/1_61-2020%20Rules.pdf
For more information concerning radio propagation, see http://www.arrl.org/propagation and the ARRL Technical Information Service at http://arrl.org/propagation-of-rf-signals. For an explanation of 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/.
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 June 18 through 24, 2020 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 67.9, 68.8, 67.8, 67.6, 67.6, 67.1, and 66.9, with a mean of 67.7. Estimated planetary A indices were 4, 5, 6, 4, 4, 4, and 5, with a mean of 4.6. Middle latitude A index was 5, 7, 7, 4, 3, 6, and 7, with a mean of 5.6.
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