The geomagnetic field was very quiet on September 10. Solar wind speed at SOHO ranged between 318 and 369 km/sec. The high latitude magnetometer at Andenes recorded quiet to unsettled levels.
Solar flux density measured at 20h UT on 2.8 GHz was 163.9 - increasing 9.9 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 153.98. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.3). Three hour interval K indices: 10000111 (planetary), 10002222 (Boulder), 00000123 (Andenes).
The background x-ray flux is at the class C2 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 18 active regions using 2K resolution (SN: 362) and in 16 active regions using 1K resolution (SN: 261) SDO/HMI images.
Region 13418 [N19W78] developed slowly and was
mostly quiet.
Region 13421 [N15W78] decayed quickly and produced a few flares. C1
flares: C1.3 @ 00:05 UT
Region 13423 [N15W13] displayed signs of decay in the intermediate
spot section. Several C
flares were recorded. M class flaring is possible. C1 flares: C1.4 @ 08:15,
C1.5 @ 09:12, C1.2 @ 10:34 UT
Region 13424 [N18E13] decayed slowly and quietly.
Region 13425 [N23E15] decayed slowly in the
trailing spot section and produced several C flares. C1
flares: C1.9 @ 23:03 UT
Region 13426 [S17W24] was quiet and stable.
Region 13427 [S28E16] was quiet and stable.
New region 13428 [N14W49] emerged on September 9 and was
numbered the next day by SWPC.
New region 13429 [N10E58] rotated into view on September 9 and
received its NOAA number the following day. The region is fairly compact in
the leading spot section, however, spots are small. An M1.3 flare was
observed at 01:28 UT on September 11. C1 flares: C1.6 @ 03:45
UT
New region 13430 [S17E09] emerged with many small spots.
New region 13431 [S07E60] rotated into view on September 9 and
developed on September 10. A magnetic delta formed in this compact region.
An M1.1 flare was recorded at 04:07 UT on September 11. C1 flares: C1.5 @
17:49, C1.5 @ 19:08 UT
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S8939 [S23W60] developed slowly and quietly.
S8940 [S21E52] was quiet and stable.
S8942 [N07E67] was quiet and stable.
New region S8946 [S20W76] emerged with a few spots.
New region S8948 [N08E37] was observed with tiny spots in an old
plage area.
New region S8949 [N09E46] emerged with tiny spots.
New region S8950 [N28E88] began to rotate into view and was
barely visible at the end of the day.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C4.7 | 01:07 | N27E39 | 13425 | GOES16 | |
| C8.4 | 01:55 | N15W04 | 13423 | GOES16 | |
| C2.5 | 02:31 | 13418 | GOES16 | ||
| C2.0 | 03:02 | 13418 | GOES16 | ||
| C3.6 | 04:35 | N15W06 | 13423 | GOES18 | |
| C2.0 | 06:44 | 13423 | GOES16 | LDE | |
| C2.2 | 11:49 | 13423 | GOES16 | ||
| C2.2 | 13:30 | N18W72 | 13418 | GOES16 | |
| C2.3 | 15:14 | 13425 | GOES16 | ||
| C2.0 | 21:06 | 13431 | GOES16 | ||
| C4.0 | 21:38 | 13431 | GOES16 | ||
| C3.1 | 22:26 | 13421 | GOES16 | simultaneous flare in AR 13423 |
September 9-10: No obviously Earth directed CMEs were observed.
September 8: A fast full halo CME with a backsided origin in the
northern hemisphere was observed from 11:48 UT in LASCO C2 imagery.
[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]
Northern hemisphere positive polarity coronal holes (CH1169 and CH1170) rotated across the central meridian on September 8-10. A negative polarity coronal hole (CH1171) in the southern hemisphere was Earth facing on September 9-10. A trans equatorial negative polarity coronal hole (CH1172) will be 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 fair to good. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet to active on September 11-15 due to effects from CH1169, CH1170, CH1171 and CH1172.
| 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 | ||||||||||
| 13418 | 2023.08.29 2023.08.30 |
5 | 3 | 3 | N19W80 | 0020 | CRO | CAO |
 |
 |
area: 0210 location: N19W78 |
| 13420 | 2023.08.30 2023.09.03 |
S22W80 |
location: S22W73 |
||||||||
| S8915 | 2023.09.01 | S20W55 | |||||||||
| 13421 | 2023.09.02 2023.09.03 |
11 | 10 | 6 | N13W78 | 0060 | EAO | CRO |
 |
 |
location: N15W78 |
| 13422 | 2023.09.03 2023.09.04 |
N14W61 |
 |
location: N11W58 |
|||||||
| 13423 | 2023.09.03 2023.09.04 |
21 | 53 | 29 | N16W16 | 0380 | EKC | EKC |
 |
 |
beta-gamma area: 0690 location: N15W13 |
| S8921 | 2023.09.03 | S14W22 | |||||||||
| S8923 | 2023.09.04 | S12W53 | |||||||||
| S8924 | 2023.09.05 | S28W49 | |||||||||
| 13424 | 2023.09.05 2023.09.05 |
3 | N17E08 | 0008 | AXX |
 |
 |
location: N18E13 |
|||
| S8926 | 2023.09.05 | N23W41 | |||||||||
| 13425 | 2023.09.05 2023.09.06 |
13 | 36 | 18 | N23E14 | 0110 | EAI | EAI |
 |
 |
area: 0170 location: N23E15 |
| S8928 | 2023.09.05 | S22W20 | |||||||||
| S8930 | 2023.09.05 | S19W58 | |||||||||
| S8931 | 2023.09.06 | N09W38 | |||||||||
| S8932 | 2023.09.06 | N30W53 | |||||||||
| S8933 | 2023.09.06 | S18W44 | |||||||||
| S8934 | 2023.09.06 | S22E30 | |||||||||
| 13426 | 2023.09.07 2023.09.07 |
1 | S14W28 | 0003 | AXX |
 |
 |
location: S17W24 | |||
| S8935 | 2023.09.07 | N25W02 | |||||||||
| 13427 | 2023.09.07 2023.09.09 |
4 | 11 | 7 | S28E16 | 0010 | CRO | DRO |
 |
 |
location: S28E16 area: 0050 |
| S8937 | 2023.09.07 | N11W03 | |||||||||
| S8939 | 2023.09.08 | 7 | 4 | S23W60 | 0030 | CRO |
 |
 |
|||
| S8940 | 2023.09.08 | 3 | 1 | S21E52 | 0010 | CRO |
 |
 |
|||
| 13429 | 2023.09.09 2023.09.10 |
9 | 11 | 5 | N09E60 | 0030 | CSO | CRI |
 |
 |
area: 0050 location: N10E58 |
| S8942 | 2023.09.09 | 1 | 1 | N07E67 | 0060 | HSX |
 |
 |
|||
| 13428 | 2023.09.09 2023.09.10 |
4 | 6 | 5 | N14W49 | 0020 | CRO | CRO |
 |
 |
area: 0050 |
| 13431 | 2023.09.09 2023.09.10 |
6 | 9 | 6 | S08E60 | 0030 | DAO | DAC |
 |
 |
beta-delta location: S07E60 area: 0180 |
| S8945 | 2023.09.09 | N27E39 |
 |
||||||||
| S8946 | 2023.09.10 | 4 | 3 | S20W76 | 0015 | BXO |
 |
||||
| 13430 | 2023.09.10 2023.09.10 |
4 | 17 | 9 | S16E09 | 0010 | BXO | DRI |
 |
was AR S8947 area: 0080 location: S17E09 |
|
| S8948 | 2023.09.10 | 4 | 2 | N08E37 | 0008 | BXO |
 |
||||
| S8949 | 2023.09.10 | 2 | 1 | N09E46 | 0006 | BXO |
 |
||||
| S8950 | 2023.09.10 | 1 | N28E88 | HSX |
 |
||||||
| Total spot count: | 77 | 182 | 100 | ||||||||
| Sunspot number: | 167 | 362 | 260 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 116 | 238 | 151 | (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): | 184 | 199 | 208 | ||||||||
| 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 | 147.1 (1) | 37.8 (2A) / 113.5 (2B) / 117.8 (2C) | (140.7 projected, +3.4) | (11.5) | |
| 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.
