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The K7RA Solar Update


The recent reporting week, December 21-27, saw counter-intuitive solar numbers, with solar flux rising but sunspot numbers in decline. This happens from time to time.

Average daily sunspot numbers declined from 137.4 to 114.4. Only three new sunspot groups emerged, two on December 22, and one on December 27. On Thursday, December 28 one more sunspot emerged and the sunspot number increased from 78 to 83.

Average daily solar flux rose from 162.7 to 172.6.

Predicted solar flux over the next month is 145 on December 29-30, 140 on December 31 to January 1, 2024, 135 on January 2-4, 150 on January 5-7, 155 on January 8-11, then 150, 155, 160, 170 and 175 on January 12-16, 180 on January 17-21, then 170, 165, 162, 155 and 145 on January 22-26, then 140 on January 27-30, and 150 on January 31 to February 3.

Predicted planetary A index is 5, 10, 8, 16, and 8 on December 29 through January 2, 2024, then 5 on January 3-7, then 10, 10 and 8 on  January 8-10, then 5 on January 11-25, then 12, 10, 10 and 8 on January 26-29, and 5 on January 30 through February 3.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, December 28, 2023 from F. K. Janda, OK1HH.

"There are active regions on the Sun that may not even be large, but whose magnetic configuration points to the possibility of solar flares, up to moderately important ones. CMEs are no exception, but they may not hit the Earth at all.

"On December 24, three moderate-importance flares were observed. At least one of them produced a CME. Based on measurements of its velocity, the collision with Earth was predicted to December 27. However, nothing happened, and despite the extension of the prediction of the onset of the disturbance by a day, calm continued on 28 December.

"For many days now there has been such a large active region on the Sun's far side that it is affecting the vibration of the entire Sun. In addition, it has been observed by NASA's Mars Perseverance rover camera. While it is primarily designed to see if there is dust in the air, it can see large sunspots and, most importantly, the sun's far side is now visible from Mars.

"So we await the return of AR 3514, which will rise in the northeastern solar disk shortly after the New Year. It will be a significant contributor to the further rise in solar activity in the days ahead. Furthermore, longer term forecasts are calling for high solar activity in the second half of January. So perhaps we will finally see an improvement in shortwave conditions."

Don't forget ARRL Straight Key Night is this weekend, for all of New Years Day (UTC), so that starts at 4:00 PM Sunday here on the Left Coast where I live. Operate CW in a casual event using your straight key or semi-automatic bug.

Recent activity:

Sun as revolving field motor:


2023 solar activity:

Cosmic spectacle:

Larger storms:

Tamitha Skov's latest report:

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For more information concerning shortwave radio propagation, see  and the ARRL Technical Information Service web page at, . For an explanation of numbers used in this bulletin, see  

An archive of past propagation bulletins is at . More good information and tutorials on propagation are at

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Sunspot numbers for December 21 through 27, 2023 were 138, 157, 123, 113, 98, 94, and 78, with a mean of 114.4. 10.7 cm flux was 193.6, 186.7, 174.2, 183.4, 166.7, 154.2, and 149.4, with a mean of 172.6. Estimated planetary A indices were 5, 4, 7, 9, 4, 5, and 4, with a mean of 5.4. Middle latitude A index was 3, 3, 5, 7, 2, 4, and 4, with a mean of 4.



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