The geomagnetic field was at quiet on July 27. Solar wind speed at SOHO ranged between 384 and 608 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 165.3 - increasing 6.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 149.06. 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: 21121221 (planetary), 22222322 (Boulder), 32122323 (Andenes).
The background x-ray flux was at the class C2 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 11 active regions using 2K resolution (SN: 224) and in 9 active regions using 1K resolution (SN: 149) SDO/HMI images.
Region 13376 [N23W85] was unstable as it
rotated almost completely out of view at the northwest limb and produced
many flares.
Region 13377 [S09W60] was mostly quiet. The two main spots
merged into one penumbra. Opposite polarity umbrae are still at some
distance, however, there is an increased chance of M class flaring.
Region 13379 [N13W35] decayed slowly and quietly.
Region 13380 [S12E17] developed slowly and merged with AR 13384. The
spot group has reversed polarities and M class flaring is possible.
Region 13385 [S16W35] decayed slowly and quietly.
Region 13386 [N12E48] developed quickly and has become a compact
region with major flare potential.
New region 13387 [N19E68] rotated into view on July 26 and was
numbered the next day by SWPC. C1 flares: C1.9 @ 18:53 UT
New region 13388 [S23E62] rotated into view on July 26 with SWPC
numbering the spot group the following day. C1 flares: C1.8 @ 11:59 UT
New region 13389 [S07E76] rotated into view early in the day.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S8795 [N21W52] reemerged with a tiny spot.
New region S8806 [S15E62] was observed with tiny
spots in an old plage area.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C6.6 | 00:38 | S11E24 | 13380 | GOES16 | |
| C5.4 | 01:10 | N22W74 | 13376 | GOES16 | simultaneous flares in ARS 13380 and 13387 |
| C3.7 | 01:26 | 13388 | GOES16 | ||
| C3.9 | 01:52 | 13376 | GOES16 | simultaneous flare in AR 13388 | |
| C4.0 | 02:22 | 13376 | GOES16 | ||
| C3.6 | 02:38 | 13387 | GOES16 | ||
| C3.0 | 03:27 | 13376 | GOES16 | ||
| C2.4 | 03:42 | 13376 | GOES16 | ||
| C2.4 | 03:54 | 13376 | GOES16 | ||
| C4.7 | 04:20 | N22W74 | 13376 | GOES16 | simultaneous similar intensity flare in AR 13388 |
| C4.8 | 04:55 | 13376 | GOES16 | ||
| C3.7 | 05:33 | 13388 | GOES16 | ||
| C3.9 | 06:22 | 13387 | GOES16 | ||
| C5.6 | 07:31 | 13376 | GOES16 | ||
| C2.6 | 08:12 | 13376 | GOES16 | ||
| C9.1 | 09:42 | 13376 | GOES16 | ||
| M1.9 | 09:50 | 13376 | GOES16 | ||
| C2.8 | 11:27 | 13376 | GOES16 | ||
| C3.2 | 12:29 | 13376 | GOES16 | ||
| C2.0 | 12:41 | 13376 | GOES16 | simultaneous flares in ARs 13377 and 13379 | |
| C2.4 | 12:59 | N26E85 | 13387 | GOES16 | |
| C2.1 | 13:32 | 13377 | GOES16 | ||
| C5.1 | 13:49 | N21W88 | 13376 | GOES16 | |
| C2.4 | 14:31 | 13376 | GOES16 | ||
| C2.5 | 15:39 | 13376 | GOES16 | ||
| C2.4 | 16:42 | 13376 | GOES16 | ||
| C3.5 | 16:53 | 13376 | GOES16 | ||
| C2.5 | 19:47 | 13387 | GOES16 | ||
| C2.2 | 20:17 | 13376 | GOES16 | ||
| C2.7 | 20:51 | 13376 | GOES16 | ||
| M1.7 | 22:34 | S21E68 | 13388 | GOES16 | |
| M1.5 | 22:52 | 13376 | GOES16 | ||
| C7.5 | 23:50 | 13386 | GOES16 |
July 25-27: 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 or near Earth facing positions.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on July 28-30.
| 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 | ||||||||||
| 13376 | 2023.07.15 2023.07.17 |
5 | 1 | N22W96 | 0140 | DAO | AXX |
 |
 |
location: N23W85 |
|
| 13377 | 2023.07.17 2023.07.17 |
2 | 4 | 2 | S09W62 | 0220 | DSO | DKC |
 |
 |
beta-delta area: 0410 location: S09W60 |
| S8775 | 2023.07.17 | S23W46 | |||||||||
| 13379 | 2023.07.18 2023.07.19 |
7 | 24 | 8 | N14W37 | 0200 | CSO | EHO |
 |
 |
area: 0330 location: N13W35 |
| S8784 | 2023.07.20 | S43W27 | |||||||||
| 13380 | 2023.07.22 2023.07.23 |
7 | 39 | 20 | S12E12 | 0110 | CSO | FAO |
 |
 |
beta-gamma area: 0200 location: S12E17 reversed polarities merged with AR 13384 on July 27 |
| 13382 | 2023.07.24 | 1 | N19W32 | 0010 | AXX | this spot is part of AR 13379 | |||||
| 13383 | 2023.07.24 | N15W22 | part of AR 13379 | ||||||||
| S8793 | 2023.07.24 | S04E04 | |||||||||
| S8794 | 2023.07.24 | N17W00 | |||||||||
| S8795 | 2023.07.24 | 1 | 1 | N21W52 | 0003 | AXX |
 |
||||
| 13384 | 2023.07.24 2023.07.25 |
4 | S15E29 | 0020 | BXO |
 |
see AR 13380 | ||||
| 13385 | 2023.07.25 2023.07.26 |
1 | 3 | 2 | S15W35 | 0020 | HRX | CRO |
 |
 |
location: S16W35 area: 0030 |
| S8799 | 2023.07.25 | N08W19 | |||||||||
| 13386 | 2023.07.25 2023.07.26 |
11 | 25 | 18 | N12E47 | 0180 | DSI | DKI |
 |
 |
area: 0680 location: N12E48 |
| 13387 | 2023.07.26 2023.07.27 |
2 | 7 | 4 | N20E66 | 0060 | HAX | CKO |
 |
 |
location: N19E68 area: 0260 |
| 13388 | 2023.07.26 2023.07.27 |
3 | 6 | 3 | S23E62 | 0030 | CSO | DSO |
 |
 |
area: 0110 |
| S8803 | 2023.07.26 | N28W20 |
 |
||||||||
| 13389 | 2023.07.27 2023.07.27 |
1 | 2 | 1 | S09E76 | 0020 | HSX | HAX |
 |
was AR S8804 location: S09E76 area: 0170 |
|
| S8806 | 2023.07.27 | 2 | S15E62 | 0002 | AXX |
 |
|||||
| Total spot count: | 44 | 114 | 59 | ||||||||
| Sunspot number: | 154 | 224 | 149 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 87 | 172 | 117 | (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): | 169 | 123 | 119 | ||||||||
| 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 |
| 2021.12 | 103.0 | 99.8 | 67.5 | 55.9 (+5.1) | 6.40 |
| 2022.01 | 103.8 | 100.5 | 55.3 | 60.1 (+4.2) | 8.92 |
| 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 | 92.5 (+5.8) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | 96.4 (+3.9) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.5 | 98.7 (+2.3) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | 101.0 (+2.3) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | 106.6 (+5.6) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 143.6 | (113.7 projected, +6.1) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 110.9 | (118.5 projected, +4.8) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 122.6 | (121.6 projected, +3.1) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 96.4 | (127.0 projected, +5.4) | 13.40 |
| 2023.05 | 155.6 | 159.2 | 137.9 | (132.7 projected, +5.7) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 163.4 | (135.9 projected, +3.2) | 8.95 |
| 2023.07 | 176.7 (1) | 123.3 (2A) / 141.6 (2B) / 148.1 (2C) | (135.4 projected, -0.5) | (8.3) | |
| 2023.08 | (136.4 projected, +1.0) | ||||
| 2023.09 | (139.8 projected, +3.4) | ||||
| 2023.10 | (141.6 projected, +1.8) | ||||
| 2023.11 | (144.2 projected max SC25, +2.6) | ||||
| 2023.12 | (143.4 projected, -0.1) | ||||
| 2024.01 | (140.1 projected, -3.3) | ||||
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
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.
