The geomagnetic field was quiet on September 15. Solar wind speed at SOHO ranged between 381 and 573 km/sec. The high latitude magnetometer at Andenes recorded quiet to major storm levels.
Solar flux density measured at 20h UT on 2.8 GHz was 139.1 - decreasing 11.5 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 154.03. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.5). Three hour interval K indices: 22122212 (planetary), 22113322 (Boulder), 33102325 (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: 212) and in 10 active regions using 1K resolution (SN: 139) SDO/HMI images.
Region 13423 [N16W79] decayed further as it
rotated to the northwest limb.
Region 13425 [N24W50] continued to lose spots and area and was quiet.
Region 13429 [N11W09] lost some spots, however the central magnetic
delta developed further. A major flare is possible. C1 flares: C1.9 @ 00:27,
C1.5 @ 04:08, C1.5 @ 05:21, C1.3 @ 08:01, C1.9 @ 08:59, C1.3 @ 21:16 UT
Region 13430 [S17W61] decayed slowly and quietly.
Region 13431 [S10W04] decayed slowly and quietly.
Region 13433 [N28E25] was quiet and stable.
New region 13434 [N08W00] was numbered by SWPC, 6 days after rotating
into view. The region decayed slowly.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S8948 [N12W32] was quiet and stable.
S8954 [N15E15] was quiet and stable.
S8960 [S13W12] decayed slowly and quietly.
S8964 [N22W40] decayed slowly and quietly.
New region S8965 [S19W23] emerged with tiny spots.
New region S8966 [S07E76] rotated into view with tiny spots.
September 16 activity: An unusually large filament eruption began just after 04h and peaked after 08h UT. The filament extended from north of AR 13433 to the west of AR 13429, and then southwards to just north of AR 13431. Early LASCO C2 imagery has a CME appearing first over the west limb at 09:12 UT and then becoming at least a partial halo CME. Earth could receive an impact on September 19.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C7.4 | 00:46 | 13429 | GOES16 | ||
| C6.9 | 00:57 | 13429 | GOES16 | ||
| C5.0 | 01:20 | 13429 | GOES16 | ||
| C2.3 | 02:01 | 13429 | GOES16 | ||
| C2.3 | 02:50 | 13429 | GOES16 | ||
| C7.5 | 03:09 | 13429 | GOES16 | ||
| C7.0 | 06:04 | 13429 | GOES16 | ||
| C2.2 | 10:17 | 13429 | GOES16 | ||
| C2.1 | 13:17 | 13429 | GOES16 | ||
| C2.0 | 15:06 | northeast limb | GOES16 | ||
| M1.7/1F | 22:29 | 13429 | GOES16 | ||
| C2.0 | 23:42 | 13429 | GOES16 |
September 13, 15: No obviously Earth directed CMEs were observed.
September 14: A long duration M1.2 (estimated) event started at 06:39
to the northeast of AR 13423 and peaked near 07:45 UT. LASCO C2 imagery
displays the leading edge of a CME off the northwest limb at 07:24 UT. This
CME later expanded to become a full halo CME. Effects could reach Earth
sometime late on September 16 or on September 17 and cause unsettled to
major storm conditions.
September 16: A CME was observed just after 09h UT, most likely due
to a filament eruption. It's too early to tell if the core of the CME could
reach Earth, but we should expect CME effects on September 19.
[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 trans equatorial negative polarity coronal hole (CH1172) was Earth facing on September 11-13.
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 fair. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to minor storm on September 16-17 due to the September 14 CME, quiet on September 18 and then quiet to minor storm on September 19-20 as components of the September 16 CME reach Earth.
| 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 | ||||||||||
| 13423 | 2023.09.03 2023.09.04 |
6 | 9 | 5 | N16W84 | 0220 | EAO | EAO |
 |
 |
location: N16W79 |
| 13424 | 2023.09.05 2023.09.05 |
N17W62 |
location: N17W56 |
||||||||
| 13425 | 2023.09.05 2023.09.06 |
8 | 11 | 5 | N23W51 | 0040 | CSO | DRO |
 |
 |
location: N24W50 |
| S8934 | 2023.09.06 | S22W35 | |||||||||
| 13427 | 2023.09.07 2023.09.09 |
S27W54 | location: S29W50 | ||||||||
| S8940 | 2023.09.08 | S22W11 | |||||||||
| 13429 | 2023.09.09 2023.09.10 |
13 | 21 | 12 | N11W09 | 0090 | DAI | DAC |
 |
 |
beta-gamma-delta area: 0240 |
| 13434 | 2023.09.09 2023.09.15 |
3 | 9 | 6 | N08W01 | 0020 | HSX | HRX |
 |
 |
|
| 13431 | 2023.09.09 2023.09.10 |
6 | 1 | S08W09 | 0012 | BXO |
 |
 |
location: S10W04 |
||
| S8945 | 2023.09.09 | N27W26 | |||||||||
| 13430 | 2023.09.10 2023.09.10 |
5 | 5 | 3 | S18W60 | 0030 | CSO | CRO |
 |
 |
|
| S8948 | 2023.09.10 | 3 | N12W32 | 0004 | BXO |
 |
 |
||||
| 13433 | 2023.09.10 2023.09.12 |
1 | 4 | 1 | N28E28 | 0090 | HSX | HSX |
 |
 |
area: 0170 location: N28E25 |
| S8954 | 2023.09.11 | 4 | N15E15 | 0005 | AXX |
 |
 |
||||
| S8955 | 2023.09.11 | N23W28 |
 |
||||||||
| S8956 | 2023.09.12 | S10W36 | |||||||||
| S8957 | 2023.09.12 | N39W56 | |||||||||
| S8958 | 2023.09.12 | S24W30 | |||||||||
| S8960 | 2023.09.13 | 1 | S13W12 | 0002 | AXX |
 |
 |
||||
| S8961 | 2023.09.13 | S13W07 | |||||||||
| S8962 | 2023.09.13 | N08W43 | |||||||||
| S8963 | 2023.09.13 | N18W15 | |||||||||
| S8964 | 2023.09.14 | 1 | 1 | N22W40 | 0003 | AXX |
 |
 |
|||
| S8965 | 2023.09.15 | 6 | 4 | S19W23 | 0015 | BXO |
 |
||||
| S8966 | 2023.09.15 | 2 | 1 | S07E76 | 0005 | BXO |
 |
||||
| Total spot count: | 36 | 82 | 39 | ||||||||
| Sunspot number: | 96 | 212 | 139 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 66 | 106 | 63 | (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): | 106 | 116 | 111 | ||||||||
| 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 | 148.5 (1) | 58.8 (2A) / 117.6 (2B) / 117.0 (2C) | (140.7 projected, +3.4) | (12.3) | |
| 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.
