Thanks to Carl, K9LA for contributing to this week's bulletin.

"SUBJ: ASWFC GEOMAGNETIC DISTURBANCE WARNING ISSUED AT 2220 UTC/10 OCTOBER 2024 BY THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE.

"A halo CME first observed on 09-Oct arrived at Earth at 10/1515UT, resulting in G4 geomagnetic conditions on 10-Oct. G4 geomagnetic conditions are expected on 11-Oct, with a chance of G5. G2 geomagnetic conditions are expected on 12-Oct, with a chance of G3 due to ongoing CME effects.

"INCREASED GEOMAGNETIC ACTIVITY EXPECTED DUE TO CORONAL MASS EJECTION FROM 11-13 OCTOBER 2024

"GEOMAGNETIC ACTIVITY FORECAST

11 Oct: G4, chance of G5

12 Oct: G2, chance of G3

13 Oct: G0-G1"

Only four new sunspot groups emerged this week. The first was on October 4, another on October 6 and two more on October 7.

Average daily sunspot number moved from 160 (Sep 26-Oct 2 period) to 182 (Oct 3-9 period), and average daily solar flux from 199 to 270.

Predicted solar flux is 215 on October 11-13, 210 on October 14-15, 200 and 205 on October 16-17, and 170 on October 18-21, then 175, 180, 185, 190, 195, 215, 230, 240, 250 and 255 on October 22-31, then 230 and 215 on November 1-2, then 205 on November 3-4, 200 and 185 on November 5-6, 175 on November 7-12, and 170 on November 13-17.

Predicted planetary A index reveals a huge disturbance at 122, 42, 12 and 12 on October 11-14, 5 on October 15-21, then 15, 10, 5, 5, 12 and 8 on October 22-27, 5 on October 28 til November 2, 12 and 8 on November 3-4, 5 on November 5-7, 8 on November 8, and 5 on November 9-17.

"Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere for October 10, 2024 from OK1HH.

"During the first ten days of October, the number of sunspot groups dropped from eleven to five, but the eruptive activity of the two largest sunspot groups did not decrease. Not only are moderate flares (M-classes, of which 34 were observed) frequent, but large events (X-classes) are also relatively common (five effects were observed, including one proton flare on 9 October). Several CMEs (coronal mass ejections) were also observed.

"After the two most active regions in particular moved to the western half of the solar disk, geomagnetic activity has increased significantly since 6 October. The most significant impacts on the state of the ionosphere were on 8 October. This will be followed by a very slow return to normal, lasting several days. A calm development can be expected after mid-October."

Reader Allison King sent this: https://nyti.ms/3YiNZtP

David Moore sent this. A new era of solar observation: https://www.sciencedaily.com/releases/2024/10/241003145438.htm

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For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation  and the ARRL Technical Information Service web page 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/

Also, check this. "Understanding Solar Indices" from September 2002 QST. https://bit.ly/3Rc8Njt

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Sunspot numbers for October 3 through 9 2024 were 194, 229, 180, 173, 167, 164, and 165, with a mean of 182. 10.7 cm flux was 245, 312, 291, 277, 265, 277 and 225, with a mean of 270. Estimated planetary A indices were 8, 8, 7, 16, 55, 58, and 19, with a mean of 24.4. Middle latitude A Index was 8, 6, 8, 13, 33, 29, and 15, with a mean of 16.