Nine new sunspot groups appeared this week, but the average daily sunspot numbers were lower.

A new sunspot group appeared every day on September 15 – 17; four more appeared on September 18, and one appeared each day on September 19 – 20, 2023.

The average daily sunspot numbers declined from 138.1 to 118.4, while the average daily solar flux declined from 159.9 to 149.3.

The autumnal equinox in the Northern Hemisphere is Friday, September 22, 2023. The change in seasons has been evident with improving conditions on 10 and 12 meters.

A fast-moving coronal mass ejection (CME) hit Earth on September 18, sparking dramatic displays of aurora across the northern tier of North America, and in Europe as far south as France.

Alaska’s college A index was 49 and 61 on September 18 – 19, while the planetary A index was 30 and 49.

Predicted solar flux is 155, 152, 153, and 155 on September 21 – 24; 160 on September 25 – 27; 135 on September 28 – 30;130, 135, 130, and 135 on October 1 – 4; 140 on October 5 – 6; 135 on October 7 – 8; 140, 145, and 145 on October 9 – 11, 150, 150, 155, and 150 on October 12 – 15, and 155, 150, 145, and 145 on October 16 – 19.

Predicted planetary A index is 8 and 15 on September 21 – 22; 12 on September 23 – 26; 5, 8, 12, and 8 on September 27 – 30; 5 on October 1 – 11; 8 on October 12, and 5 on October 13 – 19. Sunspot numbers for September 14 – 20, 2023, were 110, 96, 88, 94, 139, 143, and 159, with a mean of 118.4. The 10.7-centimeter flux was 145.2, 139.1, 140.4, 144.6, 154.5, 166.1, and 155.5, with a mean of 149.3. Estimated planetary A indices were 18, 7, 7, 16, 30, 49, and 16, with a mean of 20.4. Middle latitude A index was 13, 7, 5, 14, 21, 38, and 15, with a mean of 18.1.

Like last week, eight new sunspot groups emerged this reporting week, September 7 – 13, 2023.

One appeared on September 7, another on September 9, four more on

September 10, another on September 11, and one more on September 12.

Solar activity made a nice comeback, with average daily sunspot numbers rising from 95.4 to 138.1, and solar flux increasing from 137.6 to 159.9.

The most active geomagnetic day was September 12, when the planetary A index was 25. A “stealth CME” with an aurora visible as far south as Missouri was reported on spaceweather.com.

The average daily planetary A index decreased from 15.4 to 10.4, and middle latitude numbers decreased from 16.3 to 11.3.

The autumnal equinox in the Northern Hemisphere is on September 22 — just a week away.

It seems that the next sustained short-term peak in solar flux is a few weeks off, with values between 150 and 155 on October 12 – 17, although it’s expected to reach 150 on September 23 – 24.

The forecast shows the solar flux at 145, 145, 148, 145, and 145 on September 14 – 18; 148 on September 19 – 20; 145 on September 21 – 22; 150 on September 23 – 24; 145 on September 25; 140 on September 26 – 27; 135 on September 28 – 30; 130, 135, 130, and 135 on October 1 – 4; 140 on October 5 – 6, and 135 on October 7 – 8.

Predicted planetary A index is 12 and 15 on September 14 – 15; 8 on September 16 – 17; 5, 5, and 10 on September 18 – 20; 5, 5, and 12 on September 21 – 23; 5 on September 24 – 27; 8, 12, and 8 on September 28 – 30, and 5 on October 1 – 8. Sunspot numbers for September 7 – 13, 2023, were 135, 123, 119, 167, 173, 141, and 109, with a mean of 138.1. The 10.7-centimeter flux was 160.8, 160.9, 161.4, 163.9, 176.4, 153.5, and 142.6, with a mean of 159.9. Estimated planetary A indices were 6, 6, 8, 4, 7, 25, and 17, with a mean of 10.4. The middle latitude A index was 11, 8, 12, 6, 8, 17, and 17, with a mean of 11.3.

Seven new sunspots emerged this week: one on September 2, two on September 3, two more on September 4, one on September 5, and one on September 6.

The average daily sunspot number was up from 78.7 to 95.4, while the average daily solar flux decreased from 140.9 to 137.6.

Geomagnetic activity was higher. On September 2, the planetary A index was 38 when Earth moved through a high-speed solar wind. In Alaska, the college A index at Fairbanks was 59.

The average daily planetary A index increased from 7 to 15.4, and the average middle latitude A index rose from 8.9 to 16.3.

Predicted solar flux is 150, 155, 155, and 150 on September 7 – 10; 140 on September 11 – 13; 145, 150, 150, and 155 on September 14 – 17; 150, 155, and 150 on September 18 – 20; 145 on September 21 – 22; 150 on September 23 – 24; 145 on September 25; 140 on September 26 – 27; 135 on September 28 – 30; 130, 135, 130, and 135 on October 1 – 4, and 140 on October 5 – 6.

Predicted planetary A index is 12, 10, 5, and 5 on September 7 – 10; 8 on September 11 – 13; 10, 8, 12, 8, and 8 on September 14 – 18; 5 on September 19 – 22; 12 on September 23; 5 on September 24 – 27; 8, 12, 5, and 12 on September 28 through October 1; 12, 10, 12, and 10 on October 2 – 5, and 5 on October 6 – 10.

I observed some interesting 12-meter propagation via PSK Reporter while using FT8 at 1745 UTC on September 4. My signal was received only over a narrow, 300-mile band hugging the east coast from Maine to Florida. The signals were between 2,200 – 2,500 miles away, and nowhere else.

Three hours later, at 2045 UTC, the reception reports along the coast expanded to 600 miles, and then 2,000 – 2,600 miles.

Later, at 2300 UTC, there was the same pattern, but it was a 200-mile band spanning 2,300 – 2,500 miles wide.

The next day, at 1700 UTC, there was an arc from Virginia to south Texas stretching 1,700 – 2,300 miles wide. At 1715 UTC, it drifted to a coverage of 1,750 – 2,600 miles.

Before FT8 and PSK Reporter, there was no practical way to observe propagation. Sunspot numbers for August 31 through September 6, 2023, were 77, 83, 77, 79, 100, 121, and 131, with a mean of 95.4. The 10.7-centimeter flux was 139.9, 135.8, 131.2, 130.5, 136, 142.9, and 147.1, with a mean of 137.6. Estimated planetary A indices were 6, 12, 38, 25, 8, 11, and 8, with a mean of 15.4. Middle latitude A index was 8, 15, 25, 28, 14, 14, and 10, with a mean of 16.3.

Solar activity was down again this week, with average daily sunspot numbers dropping from 105.9 to 78.7, and the average daily solar flux dropping from 149.4 to 140.9. Only three sunspot groups appeared, occurring on August 25, 28, and 30.

There has been a gradual transition from summer to fall conditions, with 10 and 12 meters opening more frequently. The autumnal equinox is only 3 weeks away.

Geomagnetic indicators were a little lower. The average planetary A index went from 8.4 to 7, and average middle latitude numbers went from 10.1 to 8.9.

Predicted solar flux shows a peak around 168 on September 18 – 21.

Forecast values are 145 on August 31 through September 1; 150, 150, and 145 on September 2 – 4; 150 on September 5 – 6; 156 on September 7 – 8; 150 on September 9; 147 on September 10 – 11; 145, 150, 155, 150, 155, and 160 on September 12 – 17; 168 on September 18 – 21; 165, 160, and 148 on September 22 – 24; 150 on September 25 – 26, and 152, 150, 145, and 140 on September 27 – 30.

Predicted planetary A index is 5, 10, and 10 on August 31 through September 2; 5 on September 3 – 6; 8 on September 7 – 8; 5 on September 9 – 13; 12, 10, 10, and 8 on September 14 – 17; 5 on September 18 – 22; 10, 10, and 8 on September 23 – 25, and 5 on September 26 to October 2.

Read about India’s solar mission at https://bit.ly/3PiPJ1N.

Check out a video about solar flares at https://bit.ly/47X6gzC. Sunspot numbers for August 24 through 30, 2023, were 86, 77, 75, 69, 68, 82, and 94, with a mean of 78.7. The 10.7-centimeter flux was 144.1, 138.9, 139.3, 141.5, 141.7, 142.2, and 138.6, with a mean of 140.9. Estimated planetary A indices were 9, 5, 7, 11, 6, 5, and 6, with a mean of 7. The middle latitude A index was 9, 7, 9, 13, 8, 7, and 9, with a mean of 8.9.

Five new sunspot groups emerged this week: one on August 17, another on August 18, two more on August 21, and another on August 22.

Average daily sunspot numbers rose slightly from 95.7 to 105.9, while the average daily solar flux declined from 154.2 to 149.4.

There weren’t any big geomagnetic events this week to report. The average daily planetary A index changed from 6 to 8.4, while the average daily middle latitude index changed from 7.7 to 10.1.

Predicted solar flux is 150 on August 24; 155 on August 25 – 26; 160, 165, and 165 on August 27 – 29; 160, 165, and 165 on August 30 through September 1; 163 and 160 on September 2 – 3; 162 on September 4 – 5; 158 on September 6 – 7; 160 and 162 on September 8 – 9; 158 on September 10 – 11; 155 on September 12; 152 on September 13 – 15; 153 on September 16 – 18; 155 on September 19, and 158 on September 20 – 23.

Predicted planetary A index is 8 on August 24 – 25; 5, 10, and 8 on August 26 – 28; 5 on August 29 through September 5; 10, 8, and 8 on September 6 – 8; 5 on September 9 – 13; 12 on September 14; 10 on September 15 – 17, and 5 on September 18 through the end of the month.

Jeremy Gill of Seattle, Washington, shared the article, “Laboratory measurements of the physics of auroral electron acceleration by Alfvén waves,” which has information on aurora activity and the ionosphere. Read it at https://bit.ly/44sRGgh.

Read some shrill warnings of solar activity at https://bit.ly/3qHy6za, https://bit.ly/3YLsoci, https://bit.ly/3QNx8w3, and https://bit.ly/3OJRCTP.

Sunspot numbers for August 17 – 23, 2023, were 135, 112, 104, 93, 102, 96, and 99, with a mean of 105.9. The 10.7-centimeter flux was 151.9, 150.6, 150.6, 146.3, 148.7, 150.9, and 147, with a mean of 149.4. Estimated planetary A indices were 8, 11, 8, 11, 9, 8, and 4, with a mean of 8.4. Middle latitude A index was 10, 14, 8, 12, 10, 12, and 5, with a mean of 10.1.