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The K7RA Solar Update


Only four new sunspot groups emerged over the past week, one on
December 28, another on December 31, and two more on January 2 and

Solar indices sank. The average daily sunspot number declined from
114.4 to 63.4, and average daily solar flux from 172.6 to 141.9.

Average daily planetary A index rose from 8.4 to 6.7 and middle
latitude numbers from 4 to 5.1.

Predicted solar flux over the next few weeks is 130 on January 5-7,
135 on January 8-10, 140 on January 11, 155 on January 12-14, then
160, 165, 160 and 155 on January 15-18, 150 on January 19-21, then
145 and 140 on January 22-23, and 135 on January 24-26, 130 and 145
on January 27-28, 140 on January 29-30, 145 on January 31 through
February 1, 150 on February 2-4, 155 on February 5-6, 160 on
February 7, and 155 on February 8-10.

This is from the Thursday forecast, which looks substantially weaker
than the Wednesday outlook in Thursday's ARRL Letter.

Predicted planetary A index is 5, 5, 8, 10 and 8 on January 5-9,
then 5 on January 10-26, then 8, 15 and 12 on January 27-29, 8 on
January 30-31, 5 on February 1-3, then 10, 10 and 8 on February 4-6,
and 5 on February 7-18.

Solar activity looks soft of late, but perhaps we will see a double
peak in this cycle.

But look at this illustration comparing progress in the current
cycle against the last cycle, month by month since each minimum:

Page down to the second chart, labeled "Solar Cycle Comparison."

There is some confusion because of the similarity in colors.

The red line is the last cycle, probably smoothed by monthly
averages.  The blue green line inside it is probably a conventional
moving average with points on the line smoothed over a year.

The yellow line is the current cycle, also probably smoothed over a
year, and the light blue green line is the current cycle, probably
smoothed with monthly numbers.

This looks promising for more activity to come.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere, January 4, 2024, from F.K. Janda, OK1HH.

"The first celebrations of the end of the calendar year in Western
civilization are associated with the person of the canonized Pope
Silvester I, who died on the last day of the year 335. However, no
one expected that December 31, 2023, would be celebrated with
fireworks all the way on the Sun.

"Helioseismological observations focused on a large active region
approaching the northeastern limb of the solar disk from the far
side, and large spots on the far side of the Sun were seen by the
camera of the Perseverance rover on Mars. But no one actually
expected a proton solar flare, the largest in the current
eleven-year cycle.

"The X5.0 eruption in X-ray band 1 to 8 Angstrom occurred at 2155
UTC in NOAA/SWPC 3536 and was the largest observed eruption since
the X8.2 eruption on September 10, 2017. In the same sunspot group
(in the previous solar rotation), an X2.8 eruption was observed on
December 14, 2023, whereby this was the strongest since the
beginning of Solar Cycle 25 up to that point.

"In particular, however, it also contributed to expectations of a
further increase in activity in the next year or two.

"Four days later, AR3536 is no longer as large as it was on the
Sun's far side and about half the size it was in December as AR3514,
but it is still capable of producing moderate solar flares.  Now AR
3536 is approaching the central meridian from where a possible CME
(within the next week) could already be hitting Earth.  At the same
time, we expect a further increase in solar radiation , which could
improve propagation conditions in the DX bands. But of course, also
worsen if a possible magstorm lasts longer or even starts at night."

I was on a video session on Sunday with Dr. Tamitha Skov and her
Patreon subscribers. She was displaying the Sun in real time when
the big flare happened. It was quite dramatic.

She was also using a setting on that I had never
tried before. The settings are, "On All Bands, show Signals,
sent/rcvd by Anyone, using All Modes, over the last" (pick a time).

In real time we could immediately see the effects the flare had on
propagation. It was fascinating. I use this regularly now to check
worldwide propagation on all HF bands.

I asked her if her husband was an astrophysicist, and she said,
"No." She yelled, "Hey Kent! Come in here."

Kent is an actor, an acting coach, a producer, and a writer. I asked
how they met, which was hilarious. You won't read it here, but you
can email me if you want more details.

Scott Craig, WA4TTK years ago built some Windows software that sucks
up solar data from this bulletin and displays it in a nice format on
his Solar Data Plotting Utility. To update it, you just create a
plain .txt file of this bulletin and point the program to the file.

You can download it from and
also on the same page is an updated data file good through 1/3/2024.

The latest video from Dr. Tamitha Skov, WX6SWW:

An article about a powerful solar storm:

Two articles about a solar storm that will hit hard:

Send your tips, reports, observations, questions, and comments to When reporting observations, don't forget to tell us
which mode you were operating.

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 .

Also, check this article:

Instructions for starting or ending email distribution of ARRL
bulletins are at .

Sunspot numbers for December 28, 2023, through January 3, 2024, were
83, 92, 48, 55, 44, 59, and 63, with a mean of 63.4. 10.7 cm flux
was 146.7, 142.9, 139.7, 146.2, 135.7, 142.1, and 140.2, with a mean
of 141.9. Estimated planetary A indices were 3, 6, 5, 4, 10, 8, and
11, with a mean of 6.7. Middle latitude A index was 2, 6, 4, 2, 6,
8, and 8, with a mean of 5.1.




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