The geomagnetic field was unsettled to minor storm on September 26 under the influence of CME effects. Solar wind speed at SOHO ranged between 393 and 530 km/sec. The high latitude magnetometer at Andenes recorded unsettled to major storm levels.
Solar flux density measured at 20h UT on 2.8 GHz was 164.9 - increasing 26.3 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 154.82. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 28 (STAR Ap - based on the mean of three hour interval ap indices: 27.9). Three hour interval K indices: 34555333 (planetary), 34555322 (Boulder), 33434565(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 13 active regions using 2K resolution (SN: 278) and in 11 active regions using 1K resolution (SN: 195) SDO/HMI images.
Region 13435 [N09W49] decayed further and was
mostly quiet. C1 flares: C1.4 @ 01:32 UT
Region 13440 [N18W31] was quiet and stable.
Region 13442 [S09W26] was quiet and stable. The single spot could
soon merge with AR 13445.
Region 13443 [N28W86] rotated partly out of view and was quiet. C1
flares: C1.8 @ 02:47, C1.5 @ 03:08 UT
Region 13444 [N22W22] was quiet and stable.
Region 13445 [S15W23] decayed slowly in the northern spot sections.
Polarities are intermixed and a number of C flares were recorded. C1 flares:
C1.7 @ 00:49. C1.7 @ 05:39, C1.7 @ 06:20, C1.7 @ 07:39, C1.8 @ 08:56, C1.8 @
11:57, C1.6 @ 13:15, C1.4 @ 17:23, C1.6 @ 19:22, C1.6 @ 19:55 UT
Region 13447 [S22W05] developed slowly and a weak magnetic delta
structure formed in a southern central penumbra. An M class flare is
possible.
Region 13448 [N13E60] was quiet and stable.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S8993 [N14E49] developed slowly and quietly.
S8994 [S20E66] was quiet and stable.
New region S8995 [N05W01] emerged with a tiny spot before
noon, then decayed slowly.
New region S8996 [N16E42] emerged to the west
of AR S8993. Apparently SWPC believe these currently magnetically simple
spot groups are one region and has assigned AR 13449. C1 flares: C1.2 @
22:49, C1.5 @ 23:51 UT
New region S8997 [S10E52] was observed with a tiny spot in an
old plage area.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.4 | 04:02 | 13435 | GOES18 | ||
| C5.7 | 04:28 | S18W11 | 13445 | GOES16 | |
| C2.0 | 08:39 | 13445 | GOES16 | ||
| C2.5 | 09:41 | behind southeast limb | GOES16 | ||
| C2.1 | 10:13 | 13445 | GOES16 | ||
| C2.7 | 14:12 | northwest limb | S8987 | GOES16 | |
| C4.3 | 14:16 | S17W13 | 13445 | GOES16 | |
| C4.3 | 16:18 | 13445 | GOES16 | ||
| C2.2 | 23:30 | 13435 | GOES16 |
September 24-26: 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]
No obvious coronal holes are currently in an Earth facing position.
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 be quiet to active on September 27 due to lingering CME effects. Quiet to unsettled is likely on September 28-29.
| 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 | ||||||||||
| 13435 | 2023.09.16 2023.09.16 |
16 | 26 | 15 | N09W51 | 0200 | DAI | DSI |
 |
 |
beta-gamma area: 0290 location: N09W49 |
| 13439 | 2023.09.17 2023.09.18 |
S23W48 |
 |
location: S24W45 |
|||||||
| 13440 | 2023.09.17 2023.09.18 |
2 | 5 | 2 | N18W33 | 0040 | HSX | HAX |
 |
 |
location: N18W31 area: 0070 |
| 13438 | 2023.09.18 | N12W60 |
 |
location: N11W60 |
|||||||
| 13442 | 2023.09.18 2023.09.20 |
1 | 2 | 1 | S09W28 | 0020 | HAX | HRX |
 |
 |
location: S09W26 |
| 13443 | 2023.09.18 2023.09.21 |
6 | 1 | 1 | N26W95 | 0240 | ESO | ESO |
 |
location: N28W86 |
|
| 13441 | 2023.09.19 2023.09.19 |
5 | N06W89 | 0020 | CAO |
SWPC is including neighboring regions AR S8981 and S8987 in this
region location: N09W85 spotless, not sure what SWPC observed |
|||||
| S8978 | 2023.09.19 | S17W50 | |||||||||
| 13444 | 2023.09.19 2023.09.21 |
1 | 7 | 3 | N22W27 | 0005 | AXX | BXO |
 |
 |
location: N22W22 |
| 13446 | 2023.09.21 2023.09.22 |
N23E06 |
 |
location: N22E14 |
|||||||
| 13445 | 2023.09.21 2023.09.22 |
37 | 52 | 27 | S13W23 | 0220 | DAI | DAI |
 |
 |
beta-gamma location: S15W23 |
| S8988 | 2023.09.23 | N19W40 | |||||||||
| 13447 | 2023.09.24 2023.09.25 |
6 | 31 | 23 | S22W06 | 0070 | DAO | DAI |
 |
 |
beta-delta area: 0350 location: S22W05 |
| 13448 | 2023.09.24 2023.09.25 |
1 | 2 | 1 | N13E59 | 0090 | HSX | HSX |
 |
 |
area: 0200 location: N13E59 |
| S8991 | 2023.09.24 | N23E23 | |||||||||
| S8993 | 2023.09.25 | 6 | 3 | N14E49 | 0020 | CRO |
 |
 |
|||
| S8994 | 2023.09.25 | 1 | 1 | S20E66 | 0004 | AXX |
 |
 |
|||
| 13449 | 2023.09.26 | 4 | N15E47 | 0030 | CRO | SWPC includes both AR S8993 and S8996 | |||||
| S8995 | 2023.09.26 | 1 | N05W01 | 0003 | AXX |
 |
|||||
| S8996 | 2023.09.26 | 13 | 8 | N16E42 | 0040 | CRI |
 |
||||
| S8997 | 2023.09.26 | 1 | S10E52 | 0001 | AXX |
 |
|||||
| Total spot count: | 79 | 148 | 85 | ||||||||
| Sunspot number: | 179 | 278 | 195 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 112 | 187 | 124 | (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): | 197 | 152 | 156 | ||||||||
| 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 | 154.4 (1) | 114.4 (2A) / 132.0 (2B) / 139.4 (2C) | (140.7 projected, +3.4) | (15.0) | |
| 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.
