The geomagnetic field was quiet to unsettled on September 22. Solar wind speed at SOHO ranged between 351 and 396 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels.
Solar flux density measured at 20h UT on 2.8 GHz was 175.7 - increasing 36.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 154.49. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 8.3). Three hour interval K indices: 21222312 (planetary), 11333322 (Boulder), 42133345 (Andenes).
The background x-ray flux is at the class C1 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 15 active regions using 2K resolution (SN: 323) and in 14 active regions using 1K resolution (SN: 230) SDO/HMI images.
Region 13433 [N28W65] was quiet and stable.
Region 13435 [N09E04] displayed no significant changes and remains
capable of M class flaring.
Region 13437 [S18W70] decayed slowly and quietly.
Region 13438 [N11W04] decayed slowly and was mostly quiet.
Region 13439 [S24E06] decayed slowly and quietly.
Region 13440 [N17E22] was quiet and stable.
Region 13441 [N09W31] decayed slowly and quietly.
Region 13442 [S09E27] was quiet and stable.
Region 13443 [N28W39] gained spots and area and has major flare
potential. A weak magnetic delta structure is evident in the northern part
of the leading penumbra. C1 flares: C1.7 @ 01:09, C1.9 @ 15:04 UT
Region 13444 [N24E29] decayed slowly and quietly.
New region 13445 [S15E32] developed further, has significant polarity
intermixing and could produce M flares. SWPC split this spot group off AR
13442. C1 flares: C1.7 @ 00:40, C1.9 @ 00:53, C1.9 @ 01:31 UT
New region 13446 [N22E62] rotated into view on September 21 and was
numbered the next day by SWPC.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S8981 [N06W30] was quiet and stable.
S8982 [S12W21] was quiet and stable.
S8987 [N05W35] was quiet and stable.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| M1.2 | 03:36 | N15E17 | 13435 | GOES16 | filament eruption, CME |
| C5.2 | 05:26 | 13445 | GOES18 | ||
| C6.3 | 05:50 | 13443 | GOES16 | ||
| C6.5 | 07:00 | N07E04 | 13438 | GOES16 | filament eruption, CME |
| C4.2 | 07:35 | 13443 | GOES16 | ||
| C5.3/1N | 08:41 | 13443 | GOES16 | ||
| C2.6 | 09:13 | 13443 | GOES16 | ||
| C2.3 | 10:05 | 13445 | GOES16 | ||
| C2.3 | 10:48 | 13443 | GOES16 | ||
| C2.7 | 11:05 | 13443 | GOES16 | ||
| C7.3 | 11:44 | N09E09 | 13435 | GOES16 | |
| C3.8 | 12:51 | 13443 | GOES16 | ||
| C2.4 | 13:48 | 13445 | GOES16 | ||
| C2.0 | 15:30 | 13443 | GOES16 | ||
| M1.4 | 16:22 | 13443 | GOES16 | LDE | |
| M1.5 | 17:15 | 13443 | GOES16 | ||
| C2.3 | 18:39 | 13445 | GOES16 | ||
| C9.8 | 19:29 | 13437 | GOES16 | moderate type II radio sweep | |
| C3.3 | 20:31 | 13443 | GOES16 | ||
| C2.7 | 21:23 | 13443 | GOES16 | ||
| M1.9 | 23:00 | 13443 | GOES16 | similar intensity flare peaked in AR 13435 at 22:53 UT | |
| C8.6 | 23:54 | 13435 | GOES16 |
September 20: A very faint halo CME was observed in LASCO C2 imagery
after the impulsive M8 flare in AR 13435. This CME could reach Earth on
September 23.
September 21: A partial halo CME was detected in LASCO C2 imagery
following the impulsive M8.7 flare in AR 13435. This CME could reach Earth on
September 23.
September 22: Several CMEs were observed during the day. The first
one was a partial halo CME following a filament eruption to the northeast of
AR 13435 triggering an M1 flare in that region. Another filament eruption
occurred across the central meridian in the northern hemisphere (to the
north of AR 13438) just hours later and may have had Earth directed
components.
[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 negative polarity trans equatorial coronal hole (CH1175) was Earth facing on September 19. A negative polarity northern hemisphere coronal hole (CH1176) formed after a filament eruption early on September 22. CH1176 rotated across the central meridian that day and on September 23.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor to very poor. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is likely to become disturbed on September 23-25 due to several CMEs observed on September 20-22. Unsettled to minor storm conditions are possible.
| 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 | ||||||||||
| 13433 | 2023.09.10 2023.09.12 |
1 | 1 | 1 | N28W66 | 0060 | HSX | HSX |
 |
 |
area: 0110 location: N28W65 |
| S8966 | 2023.09.15 | S05W21 |
 |
||||||||
| 13435 | 2023.09.16 2023.09.16 |
6 | 26 | 15 | N09E03 | 0280 | DKI | DKC |
 |
 |
beta-gamma area: 0500 location: N09E04 |
| S8968 | 2023.09.16 | N16W58 | |||||||||
| 13439 | 2023.09.17 2023.09.18 |
2 | 8 | 3 | S24E05 | 0030 | HSX | CAO |
 |
 |
area: 0050 location: S24E06 |
| 13437 | 2023.09.17 2023.09.18 |
5 | 7 | 3 | S18W69 | 0120 | DSO | EAO |
 |
 |
location: S18W70 area: 0170 |
| 13440 | 2023.09.17 2023.09.18 |
1 | 5 | 3 | N18E21 | 0060 | HSX | CAO |
 |
 |
location: N17E22 area: 0130 |
| 13438 | 2023.09.18 | 12 | 21 | 11 | N11W05 | 0050 | BXI | DRI |
 |
 |
area: 0070 |
| 13442 | 2023.09.18 2023.09.20 |
1 | 1 | 1 | S09E25 | 0030 | HSX | HSX |
 |
 |
area: 0050 location: S09E27 |
| 13443 | 2023.09.18 2023.09.21 |
15 | 33 | 20 | N28W40 | 0150 | DAI | EAI |
 |
 |
beta-delta location: N28W39 area: 0430 |
| S8976 | 2023.09.18 | N24E02 | |||||||||
| 13441 | 2023.09.19 2023.09.19 |
8 | 6 | 3 | N09W31 | 0030 | CRI | CRO |
 |
 |
|
| S8978 | 2023.09.19 | S17W11 | |||||||||
| 13444 | 2023.09.19 2023.09.21 |
1 | 4 | 1 | N24E28 | 0010 | AXX | BXO |
 |
 |
location: N24E29 |
| S8980 | 2023.09.19 | S05W33 | |||||||||
| S8981 | 2023.09.20 | 10 | 5 | N06W30 | 0040 | DRO |
 |
 |
|||
| S8982 | 2023.09.20 | 4 | S12W21 | 0006 | AXX |
 |
 |
||||
| 13446 | 2023.09.21 2023.09.22 |
3 | 4 | 3 | N23E63 | 0010 | BXO | CRO |
 |
 |
area: 0025 location: N22E62 |
| 13445 | 2023.09.21 2023.09.22 |
9 | 34 | 17 | S15E33 | 0100 | DAI | DRI |
 |
 |
beta-gamma location: S15E32 area: 0270 |
| S8987 | 2023.09.21 | 9 | 4 | N05W35 | 0030 | CRO |
 |
 |
|||
| Total spot count: | 64 | 173 | 90 | ||||||||
| Sunspot number: | 184 | 323 | 230 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 112 | 231 | 148 | (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): | 202 | 178 | 184 | ||||||||
| 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 |
| 2022.02 | 109.1 | 106.5 | 60.9 | 64.7 (+4.6) | 10.46 |
| 2022.03 | 117.0 | 115.8 | 78.6 | 68.7 (+4.0) | 10.20 |
| 2022.04 | 130.8 | 131.7 | 84.0 | 73.0 (+4.3) | 11.79 |
| 2022.05 | 133.8 | 136.8 | 96.5 | 77.4 (+4.4) | 7.48 |
| 2022.06 | 116.1 | 119.8 | 70.3 | 81.1 (+3.7) | 8.20 |
| 2022.07 | 125.4 | 129.5 | 91.4 | 86.7 (+5.6) | 9.51 |
| 2022.08 | 114.2 | 117.1 | 74.6 | 92.6 (+5.9) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | 96.5 (+3.9) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.5 | 98.9 (+2.4) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | 101.1 (+2.2) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | 106.7 (+5.6) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 144.4 | 113.4 (+6.7) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 111.3 | 117.9 (+3.5) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 123.3 | (121.0 projected, +3.1) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 96.4 | (126.3 projected, +5.3) | 13.40 |
| 2023.05 | 155.6 | 159.2 | 137.9 | (131.9 projected, +5.6) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 163.4 | (135.1 projected, +3.2) | 8.95 |
| 2023.07 | 176.4 | 182.2 | 159.1 | (135.5 projected, +0.4) | 8.15 |
| 2023.08 | 153.7 | 157.6 | 114.9 | (137.3 projected, +1.8) | 7.19 |
| 2023.09 | 151.5 (1) | 90.7 (2A) / 123.6 (2B) / 127.3 (2C) | (140.7 projected, +3.4) | (14.2) | |
| 2023.10 | (142.5 projected, +1.8) | ||||
| 2023.11 | (145.1 projected max SC25, +2.6) | ||||
| 2023.12 | (144.2 projected, -0.9) | ||||
| 2024.01 | (141.4 projected, -2.8) | ||||
| 2024.02 | (141.2 projected, -0.2) | ||||
| 2024.03 | (140.8 projected, -0.4) | ||||
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
Looking back 6 months, the 365d smoothed values for solar flux and all sunspot numbers with the exception of NOAA's, are all above their solar cycle 24 peak. The first peak of solar cycle 25 is forecast to be between July 7 and 10, 2023 (solar flux on July 7, ISN and STAR 1K and 2K all have that peak on July 9, while NOAA peaks on July 10). This is unlikely to be the final peak of SC25, however, there is a small probability that it is the actual sunspot and solar flux maximum.
--------------------------------------------------------------------------------------
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.
