The geomagnetic field was at quiet levels on October 21. Solar wind speed at SOHO ranged between 329 and 387 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux was at background levels.
Solar flux density measured at 20h UT on 2.8 GHz was 163.9 - decreasing 8.5 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 180.45. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 180.45 on April 22, 2024). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.8). Three hour interval K indices: 10110122 (planetary), 11122312 (Boulder), 20010155 (Andenes).
The background x-ray flux is at the class C4 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 18 active regions using 2K resolution (SN: 312) and in 17 active regions using 1K resolution (SN: 236) SDO/HMI images.
AR 13856 [N09W75] decayed slowly and quietly.
AR 13857 [S07W26] decayed slowly and quietly.
AR 13858 [S15W30] was quiet and stable.
AR 13859 [S12W57] decayed slowly and was mostly
quiet.
AR 13860 [S06W43] decayed slowly and quietly.
AR 13862 [S16E21] was quiet and stable.
AR 13863 [S08E31] decayed slowly and was mostly quiet.
AR 13864 [N25E35] was quiet and stable.
AR 13865 [S22E49] was quiet and stable.
New AR 13866 [S12E57] rotated into view on October 20 and was
numbered the next day by SWPC.
New AR 13867 [S21E31] emerged on October 20 and received its NOAA
number the following day.
New AR 13868 [S11E74] rotated into view with a large spot.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S10242 [S31W15] decayed slowly and quietly.
S10252 [N09W17] reemerged with tiny spots.
S10260 [S19W01] was quiet and stable.
New region S10264 [N25W08] emerged with a tiny spot.
New region S10265 [S25E49] emerged with tiny
spots before noon, then decayed slowly.
New region S10266 [N09E68] emerged with a tiny spot.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.3 | 01:08 | 13863 | GOES16 | ||
| C3.4 | 02:06 | behind southwest limb | 13854 | GOES16 | |
| C3.0 | 02:58 | behind southeast limb | GOES16 | ||
| C2.2 | 06:05 | 13859 | GOES16 | ||
| C2.5 | 06:56 | 13866 | GOES16 | ||
| C6.2 | 10:00 | behind southeast limb | GOES16 | LDE | |
| C4.8 | 11:35 | southeast limb | GOES16 | ||
| C3.9 | 15:58 | 13858 | GOES16 | ||
| C4.3 | 17:21 | 13863 | GOES16 | ||
| C4.6 | 18:32 | southeast limb | GOES16 | ||
| C4.7 | 21:20 | southeast limb | GOES16 |
October 19-21: No obviously Earth directed CMEs were observed.
[Coronal
hole history (since October 2002)]
[Compare today's report to the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago]
A positive polarity northern hemisphere coronal hole (CH1248) was Earth facing on October 18-19. A recurrent negative polarity trans equatorial coronal hole (CH1249) will rotate across the central meridian on October 25.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be at quiet to active levels on October 22-23 due to effects from CH1248. Mostly quiet conditions are likely on October 24. October 25-26 could see unsettled and active intervals in response to the arrival of a high speed stream associated with CH1249.
| Coronal holes (1) | Coronal mass ejections (2) | M and X class flares (3) |
1) Effects from a coronal hole could
reach Earth within the next 5 days. When the high speed stream has arrived
the color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96
hours.
3) There is a possibility of either M or X class flares within the
next 48 hours.
Green: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.
(Click on image for 2K resolution).
4K resolution.
Compare to the previous
day's image. 0.5K image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue is positive.
Data for all officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers. SWPC data considered to be not sufficiently precise (location, area, classification) are colored red.
| Active region | SWPC date numbered STAR detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC/ USAF |
Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 13856 | 2024.10.10 2024.10.13 |
4 | 3 | 3 | N10W73 | 0120 | DAO | DAO |
 |
 |
beta-gamma location: N09W75 |
| 13858 | 2024.10.13 2024.10.14 |
6 | S15W35 | 0008 | BXO |
 |
 |
location: S15W30 |
|||
| 13857 | 2024.10.13 2024.10.14 |
4 | 12 | 6 | S06W26 | 0030 | CAO | CRO |
 |
 |
location: S07W26 |
| 13859 | 2024.10.15 2024.10.15 |
17 | 29 | 13 | S12W54 | 0220 | CSI | DAI |
 |
 |
area: 0150 location: S12W57 |
| S10240 | 2024.10.15 | N26W37 |
 |
||||||||
| S10241 | 2024.10.15 | N07W30 | |||||||||
| S10242 | 2024.10.15 | 1 | 1 | S31W15 | 0002 | AXX |
 |
 |
|||
| S10244 | 2024.10.16 | S03W45 | |||||||||
| 13860 | 2024.10.16 2024.10.17 |
2 | 9 | 5 | S06W42 | 0030 | CSO | CSO |
 |
|
location: S06W43 |
| 13863 | 2024.10.17 2024.10.19 |
16 | 16 | 14 | S08E31 | 0220 | DAI | DAI |
 |
 |
area: 0350 |
| S10251 | 2024.10.18 | S04W45 | |||||||||
| S10252 | 2024.10.18 | 4 | 3 | N09W17 | 0012 | BXO |
 |
||||
| 13862 | 2024.10.18 2024.10.19 |
2 | 10 | 2 | S16E24 | 0010 | AXX | CRO |
 |
 |
location: S16E21 |
| 13865 | 2024.10.19 2024.10.20 |
3 | 5 | 2 | S22E51 | 0020 | CSO | CAO |
 |
 |
location: S22E49 area: 0050 |
| 13864 | 2024.10.19 2024.10.20 |
1 | 4 | 2 | N25E33 | 0010 | AXX | BXO |
 |
 |
location: N25E35 |
| S10257 | 2024.10.19 | N13W39 | |||||||||
| S10258 | 2024.10.19 | S17W40 | |||||||||
| 13866 | 2024.10.20 2024.10.21 |
6 | 13 | 8 | S12E58 | 0030 | CAI | DRI |
 |
 |
location: S12E57 |
| S10260 | 2024.10.20 | 6 | 2 | S19W01 | 0013 | CRO |
 |
 |
|||
| S10261 | 2024.10.20 | N17E45 |
 |
||||||||
| 13867 | 2024.10.20 2024.10.21 |
2 | 9 | 1 | S23E32 | 0010 | BXO | CRO |
 |
 |
location: S21E31 |
| 13868 | 2024.10.21 2024.10.21 |
1 | 1 | 1 | S11E75 | 0180 | HSX | HHX |
 |
location: S11E74 area: 0280 was AR S10263 |
|
| S10264 | 2024.10.21 | 1 | 1 | N25W08 | 0003 | AXX |
 |
||||
| S10265 | 2024.10.21 | 2 | 1 | S25E48 | 0004 | AXX |
 |
||||
| S10266 | 2024.10.21 | 1 | 1 | N09E48 | 0002 | AXX |
 |
||||
| Total spot count: | 58 | 132 | 66 | ||||||||
| Sunspot number: | 168 | 312 | 236 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 98 | 182 | 116 | (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10) | |||||||
| Relative sunspot number (Wolf number): | 185 | 172 | 189 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average
ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2014.02 | 170.3 (cycle peak) |
166.3 | 146.1 (SC24 peak) | 110.5 | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (SC24 solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (SC24 peak) |
| 2019.11 | 70.2 | 68.7 | 0.5 | 2.0 (-0.6) (Solar minimum using 365d smoothing: November 17, 2019) |
4.19 |
| 2019.12 | 70.8 | 68.6 | 1.6 | 1.8 (-0.2) (ISN 13 months smoothed solar minimum) |
3.22 |
| 2023.01 | 182.4 | 176.6 | 144.4 | 113.3 (+6.6) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 111.3 | 117.8 (+3.5) | 14.48 |
| 2023.03 | 157.2 | 155.6 | 123.3 | 121.1 (+3.3) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 97.6 | 122.9 (+1.8) | 13.40 |
| 2023.05 | 155.6 | 159.2 | 137.4 | 124.2 (+1.3) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 160.5 | 125.3 (+1.1) | 8.95 |
| 2023.07 | 176.4 | 182.2 | 160.0 | 124.6 (-0.7) | 8.15 |
| 2023.08 | 153.7 | 157.6 | 114.8 | 124.3 (-0.3) | 7.19 |
| 2023.09 | 154.4 | 156.0 | 134.2 | 124.0 (-0.3) | 14.26 |
| 2023.10 | 142.8 | 141.9 | 99.4 | 124.8 (+0.8) | 8.16 |
| 2023.11 | 153.5 | 150.2 | 105.4 | 127.8 (+3.0) | 12.20 |
| 2023.12 | 151.1 | 146.4 | 114.2 | 129.4 (+1.6) | 9.60 |
| 2024.01 | 164.6 | 159.3 | 126.0 | 131.1 (+1.7) | 5.46 |
| 2024.02 | 172.5 | 168.3 | 123.0 | 136.8 (+5.7) | 5.31 |
| 2024.03 | 154.4 | 152.9 | 103.7 | 141.3 (+4.5) | 11.03 |
| 2024.04 | 161.3 | 162.6 | 136.5 | (145.3 projected, +4.0) | 9.69 |
| 2024.05 | 187.7 | 191.9 | 171.7 | (151.6 projected, +6.3) | 23.56 (SC25 peak) |
| 2024.06 | 184.3 | 190.2 | 164.2 | (155.5 projected, +3.9) | 10.24 |
| 2024.07 | 196.6 |
203.0 | 196.5 | (158.4 projected, +2.9) | 7.13 |
| 2024.08 | 246.1 (cycle peak) |
252.2 | 215.5 (SC25 peak) | (160.4 projected, +2.0) | 15.96 |
| 2024.09 | 195.7 | 197.8 | 141.4 | (163.1 projected, +2.7) | 15.36 |
| 2024.10 | 216.1 (1) | 101.3 (2A) / 149.6 (2B) / 202.6 (2C) ISN preliminary average: 156 |
(165.4 projected, +2.3) | (23.3) | |
| 2024.11 | (163.7 projected, -1.7) | ||||
| 2024.12 | (160.7 projected, -3.0) | ||||
| 2025.01 | (156.3 projected, -4.4) | ||||
| 2025.02 | (149.6 projected, -6.7) | ||||
| 2025.03 | (144.8 projected, -4.8) | ||||
| 2025.04 | (141.6 projected, -3.2) | ||||
1) Running average based on the daily 20:00 UTC observed solar flux value
at 2800 MHz and any corrections applied to that measurement.
2A) Current impact on the monthly sunspot number based on the Boulder
(NOAA/SWPC) sunspot number (accumulated daily sunspots / month days).
2B) Boulder SN current month average to date.
2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap
indices. Values in red
are based on the definitive international
GFZ Potsdam WDC ap
indices.
4) Source: WDC-SILSO, Royal Observatory
Of Belgium, Brussels
September 2024 saw a significant decrease in sunspot numbers compared to the previous month, however, activity was still fairly high. The average solar flux for the month ranks as number 3 of all months during SC25. Taking into account that we started seeing high sunspot numbers April 14, 2024, the most likely candidate for solar maximum would be at or just after October 14, 2024. Assuming that the average sunspot number from now until April 14, 2025 becomes 150, we would be looking at a 365 days smoothed sunspot maximum of 164.5 centered on October 14. Should the average sunspot number for that period become 160 we would get a peak near 169.7.
--------------------------------------------------------------------------------------
This report has been prepared by Jan Alvestad. It is based on the analysis of data from whatever sources are available at the time the report is prepared. All time references are to Universal Time. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
