The geomagnetic field was quiet to unsettled on May 24 under the influence of a high speed stream associated with CH1149. Solar wind speed at SOHO ranged between 508 and 631 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 164.1 - increasing 23.3 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 140.76. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 10.3). Three hour interval K indices: 23123233 (planetary), 23113423 (Boulder), 44234354 (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 12 active regions using 2K resolution (SN: 322) and in 10 active regions using 1K resolution (SN: 213) SDO/HMI images.
Region 13310 [S20W18] became slightly less
complex as most of the small positive polarity spots disappeared.
Region 13311 [N19W02] decayed in the intermediate and trailing spot
sections. The magnetic delta decreased in size. The leading spot section was
split off into a new region. Further M class flares are possible. C1 flares:
C1.5 @ 02:11, C1.8 @ 05:24, C1.9 @ 22:23 UT
Region 13312 [S25E04] decayed slowly and was mostly quiet. C1 flares:
C1.4 @ 12:52, C1.5 @ 13:15 UT
Region 13313 [N22E11] was quiet and stable.
Region 13315 [S18E33] developed significantly and has minor polarity
intermixing. Further M class flares are possible.
Spotted regions not observed (or interpreted
differently) by SWPC:
S8580 [N20W27] was quiet and stable.
S8586 [S28W45] decayed slowly and quietly.
New region S8588 [S13W13] emerged with several
spots to the north of AR 13310.
New region S8589 [S20E12] was observed with tiny spots in an old
plage area.
New region S8590 [N15W17] was split off from AR 13311 as negative
polarity spots emerged to the southeast of the previous leader spot of that
region.
New region S8591 [N11E50] emerged with a tiny spot.
New region S8592 [N08E63] emerged with tiny
spots.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.7 | 03:50 | 13311 | GOES16 | ||
| C2.8 | 04:08 | 13311 | GOES16 | ||
| C2.4 | 07:59 | S8590 | GOES16 | incorrectly attributed to AR 13312 by SWPC | |
| C5.0 | 08:37 | 13311 | GOES16 | ||
| C2.3 | 09:31 | 13311 | GOES16 | ||
| M1.0 | 09:58 | 13311 | GOES16 | ||
| C5.9 | 10:06 | S8590 | GOES16 | ||
| C6.7 | 10:26 | 13311 | GOES16 | ||
| C2.0 | 13:47 | 13311 | GOES16 | ||
| C2.4 | 15:01 | 13311 | GOES16 | ||
| C2.7 | 15:32 | 13311 | GOES16 | ||
| C2.0 | 16:24 | 13311 | GOES16 | ||
| C4.3 | 17:10 | 13311 | GOES16 | ||
| M1.9/1F | 17:26 | 13311 | GOES16 | ||
| M1.0 | 18:00 | 13315 | GOES16 | ||
| C3.1 | 18:48 | 13315 | GOES16 | ||
| C3.8 | 18:55 | 13311 | GOES16 | ||
| C5.1 | 19:10 | 13311 | GOES16 | incorrectly attributed to AR 13312 by SWPC | |
| C3.5 | 19:51 | 13311 | GOES16 | ||
| C2.8 | 20:12 | 13311 | GOES16 | ||
| C2.3 | 22:23 | 13311 | GOES16 | simultaneous flare in AR S8590 | |
| C2.6 | 22:41 | 13312 | GOES16 |
May 23-24: No obviously Earth directed CMEs were
observed.
May 22: A faint CME, mostly over the southeast limb, but with faint
traces over the southwest limb as well, was observed after the M1 flare in
AR 13312. It is uncertain if there was any Earth directed component with
this CME.
[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 recurrent trans equatorial coronal hole (CH1149) rotated across the central meridian on May 20-22.
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.
Quiet to unsettled conditions are likely on May 25-26 due to effects from CH1149. Quiet conditions are expected for May 27.
| Coronal holes (1) | Coronal mass ejection (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 | ||||||||||
| 13310 | 2023.05.16 2023.05.17 |
11 | 24 | 9 | S20W18 | 0480 | CHO | CHO |
 |
 |
area: 0700 |
| 13311 | 2023.05.17 2023.05.18 |
39 | 61 | 41 | N18W08 | 0470 | EAI | ESI |
 |
 |
beta-gamma-delta location: N19W02 |
| 13312 | 2023.05.18 2023.05.19 |
15 | 32 | 19 | S25E02 | 0050 | CRO | DRO |
 |
 |
location: S25E04 |
| 13313 | 2023.05.18 2023.05.19 |
2 | 6 | 1 | N22E06 | 0100 | HSX | CSO |
 |
 |
area: 0170 |
| 13314 | 2023.05.19 2023.05.20 |
15 | N12W17 | 0130 | CSO |
merged with AR 13311 on 2023.05.22 SWPC resurrected the region on 2023.05.24 see AR S8590 |
|||||
| S8575 | 2023.05.19 | N37W44 | |||||||||
| S8578 | 2023.05.21 | N17W58 | |||||||||
| S8579 | 2023.05.21 | S02W12 | |||||||||
| S8580 | 2023.05.22 | 4 | 3 | N20W27 | 0015 | BXO |
 |
 |
|||
| S8582 | 2023.05.22 | S09W16 |
 |
||||||||
| 13315 | 2023.05.22 2023.05.23 |
11 | 31 | 18 | S17E32 | 0130 | DAI | DAI |
 |
 |
beta-gamma location: S18E33 area: 0300 |
| S8584 | 2023.05.22 | S19E13 | |||||||||
| S8585 | 2023.05.22 | N41W17 | |||||||||
| S8586 | 2023.05.23 | 1 | S28W45 | 0001 | AXX |
 |
 |
||||
| S8587 | 2023.05.23 | N25W32 |
 |
||||||||
| S8588 | 2023.05.24 | 9 | 5 | S13W13 | 0040 | DRO |
 |
||||
| S8589 | 2023.05.24 | 6 | 2 | S20E12 | 0010 | AXX |
 |
||||
| S8590 | 2023.05.24 | 24 | 14 | N15W17 | 0200 | DSI |
 |
beta-gamma split off from AR 13311 |
|||
| S8591 | 2023.05.24 | 1 | N11E50 | 0002 | AXX |
 |
|||||
| S8592 | 2023.05.24 | 3 | 1 | N08E63 | 0005 | BXO |
 |
||||
| Total spot count: | 93 | 202 | 113 | ||||||||
| Sunspot number: | 153 | 322 | 213 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 126 | 238 | 149 | (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): | 168 | 177 | 170 | ||||||||
| 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 |
| 2021.09 | 87.0 | 88.2 | 51.3 | 40.2 (+4.8) | 6.33 |
| 2021.10 | 88.9 | 88.3 | 37.4 | 45.2 (+5.0) | 7.38 |
| 2021.11 | 86.2 | 84.4 | 34.8 | 50.8 (+5.6) | 9.83 |
| 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 | (100.4 projected, +1.7) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | (104.1 projected, +3.7) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 143.6 | (110.1 projected, +6.0) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 110.9 | (115.2 projected, +5.1) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 122.6 | (118.3 projected, +3.1) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 96.4 | (123.7 projected, +5.4) | 13.40 |
| 2023.05 | 155.7 (1) | 95.5 (2A) / 123.4 (2B) / 151.8 (2C) | (129.3 projected, +5.6) | (12.2) | |
| 2023.06 | (132.5 projected, +3.2) | ||||
| 2023.07 | (132.0 projected, -0.5) | ||||
| 2023.08 | (133.0 projected, +1.0) | ||||
| 2023.09 | (136.4 projected, +3.4) | ||||
| 2023.10 | (138.3 projected, +1.9) | ||||
| 2023.11 | (141.4 projected, +3.1) | ||||
| 2023.12 | (142.5 projected max SC25) | ||||
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: SIDC-SILSO.
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.
