The geomagnetic field was quiet to active on May 1 under the influence of effects from CH1217 and weak CME effects. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux was at background levels at the end of the day.
Solar flux density measured at 20h UT on 2.8 GHz was 134.8 - increasing 21.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 158.52. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 158.71 on October 28, 2023). The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.6). Three hour interval K indices: 42201121 (planetary), 42202232 (Boulder), 52202133 (Andenes).
The background x-ray flux is at the class B9 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 16 active regions using 2K resolution (SN: 311) and in 14 active regions using 1K resolution (SN: 217) SDO/HMI images.
Region 13654 [S07W74] decayed slowly losing
area and spots. A long duration C5.4 event peaking at 06:57 UT was
observed just south of this group, a partial halo CME was later observed in
LASCO imagery. C1 flares: C1.3 @ 05:46, C1.1 @ 18:57 UT
Region 13655 [S27W70] decayed slowly and quietly.
Region 13660 [N09E05] decayed in the trailing spot section.
Region 13661 [N23E37] developed slowly and quietly.
Region 13662 [N29W01] developed slowly and quietly.
Region 13663 [N26E24] gained spots and area and has a weak magnetic
delta configuration. Further M class flaring is likely. C1 flares: C1.4 @
03:50, C1.7 @ 10:56, C1.4 @ 18:02, C1.9 @ 18:17, C1.6 @ 18:37, C1.9 @ 20:06
UT
New region 13664 [S18E68] rotated into view on April 30 and was
numbered the next day by SWPC. C flares are possible. C1 flares: C1.2 @
20:42, C1.2 @ 00:04 (flare began at 23:59) UT
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S9637 [S11W20] was quiet and stable.
S9656 [S04W41] was quiet and stable.
S9657 [N30W32] was quiet and stable.
S9660 [N11E55] was quiet and stable.
S9661 [S20E15] was quiet and stable.
New region S9662 [N20E19] emerged with tiny spots.
New region S9663 [S11W61] emerged with tiny spots.
New region S9664 [S28W35] emerged with a tiny spot.
Minor update added at 15:25 UT: A weak solar wind shock was observed at DSCOVR at 13:16 UT on May 2. Minor geomagnetic storming is possible.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| M1.1 | 00:15 | 13654 | GOES16 | ||
| C5.4 | 06:57 | near southwest limb | GOES16 | Long duration event, partial halo CME | |
| C5.8 | 07:44 | 13664 | GOES16 | ||
| C5.8 | 07:58 | 13664 | GOES16 | ||
| M1.8 | 14:32 | S05W75 | 13654 | GOES16 | |
| M1.9 | 14:44 | GOES16 | |||
| C2.7 | 15:50 | GOES16 | |||
| C2.1 | 16:50 | 13663 | GOES16 | ||
| C2.2 | 16:57 | GOES16 | |||
| C3.7 | 17:11 | N24E26 | 13663 | GOES16 | |
| M1.8 | 22:31 | N25E24 | 13663 | GOES16 |
April 29-30: No obviously Earth directed CMEs were observed.
May 1: A partial halo CME was observed after a very long duration
event to the south of AR 13654. Components of this CME could reach Earth on
May 4.
[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 positive polarity northern hemisphere coronal hole (CH1218) was Earth facing on April 30. A positive polarity northern hemisphere coronal hole (CH1219) will be Earth facing on May 1-2. A positive polarity trans equatorial coronal hole (CH1220) will rotate across the central meridian on May 3.
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 to unsettled on May 2. Effects from CH1218 could cause quiet to unsettled conditions on May 3, while a disturbance related to CH1219 could cause quiet to active conditions on May 4-5. The May 1 CME could reach Earth on May 4 and cause unsettled to minor storm conditions. Effects from CH1220 will likely cause quiet to active conditions on May 6.
| 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 | ||||||||||
| 13657 | 2024.04.19 2024.04.21 |
S14W88 | location: S15W81 | ||||||||
| 13654 | 2024.04.20 2024.04.21 |
18 | 11 | 9 | S07W76 | 0400 | FKC | FKC |
 |
 |
location: S07W74 area: 0600 |
| 13655 | 2024.04.21 | 1 | 1 | 1 | S27W71 | 0030 | HSX | HAX |
 |
 |
location: S27W70 |
| 13656 | 2024.04.21 2024.04.21 |
S12W63 | location: S13W59 | ||||||||
| 13659 | 2024.04.24 2024.04.25 |
S13W50 | |||||||||
| S9637 | 2024.04.25 | 15 | 3 | S11W20 | 0025 | CRO |
 |
 |
|||
| S9638 | 2024.04.25 | N04W35 | |||||||||
| S9639 | 2024.04.25 | N05W16 | |||||||||
| S9641 | 2024.04.26 | N04W41 |
 |
||||||||
| 13660 | 2024.04.26 2024.04.27 |
5 | 2 | N11E09 | 0010 | AXX |
 |
 |
location: N09E05 | ||
| S9646 | 2024.04.27 | S12W31 | |||||||||
| 13662 | 2024.04.27 2024.04.29 |
10 | 24 | 14 | N30W01 | 0070 | DAO | DAI |
 |
 |
area: 0170 location: N29W01 |
| S9649 | 2024.04.27 | N04W50 | |||||||||
| 13661 | 2024.04.28 2024.04.29 |
1 | 8 | 4 | N24E39 | 0040 | HSX | DSO |
 |
 |
area: 0060 location: N23E39 two groups? |
| S9651 | 2024.04.28 | N06W17 | |||||||||
| 13663 | 2024.04.29 2024.04.30 |
9 | 42 | 24 | N26E25 | 0060 | DSO | DAI |
 |
 |
beta-gamma-delta location: N26E24 area: 0140 |
| S9653 | 2024.04.29 | S04E01 | |||||||||
| 13664 | 2024.04.30 2024.05.01 |
5 | 21 | 9 | S18E64 | 0040 | DAO | EAI |
 |
 |
area: 0180 location: S18E68 |
| S9656 | 2024.04.30 | 2 | S04W41 | 0002 | BXO |
 |
 |
||||
| S9657 | 2024.04.30 | 2 | 1 | N30W32 | 0004 | AXX |
 |
 |
|||
| S9658 | 2024.04.30 | N12W15 |
 |
||||||||
| S9659 | 2024.04.30 | N20E21 |
 |
||||||||
| S9660 | 2024.04.30 | 5 | 2 | N11E55 | 0010 | BXO |
 |
 |
|||
| S9661 | 2024.04.30 | 8 | 3 | S20E15 | 0015 | AXX |
 |
 |
|||
| S9662 | 2024.05.01 | 3 | 2 | N20E19 | 0010 | CRO |
 |
||||
| S9663 | 2024.05.01 | 2 | 2 | S11W61 | 0007 | BXO |
 |
||||
| S9664 | 2024.05.01 | 1 | S28W35 | 0002 | AXX |
 |
|||||
| S9665 | 2024.05.01 | 1 | 1 | S05E84 | 0005 | HRX |
 |
||||
| Total spot count: | 44 | 151 | 77 | ||||||||
| Sunspot number: | 104 | 311 | 217 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 79 | 195 | 121 | (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): | 114 | 171 | 174 | ||||||||
| 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 |
| 2022.10 | 133.5 | 132.7 | 95.5 | 98.9 (+2.4) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | 101.2 (+2.3) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | 106.7 (+5.5) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 144.4 | 113.3 (+6.6) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 111.3 | 117.8 (+3.5) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 123.3 | 121.1 (+3.3) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 97.6 | 122.9 (+1.8) | 13.40 |
| 2023.05 | 155.6 | 159.2 | 137.4 | 124.2 (+1.3) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 160.5 | 125.3 (+1.1) (SC25 solar max candidate) |
8.95 |
| 2023.07 | 176.4 | 182.2 | 160.0 | 124.4 (-0.9) | 8.15 |
| 2023.08 | 153.7 | 157.6 | 114.8 | 124.1 (-0.3) | 7.19 |
| 2023.09 | 154.4 | 156.0 | 134.2 | 123.9 (-0.2) | 14.26 |
| 2023.10 | 142.8 | 141.9 | 99.4 | 124.8 (+0.9) | 8.16 |
| 2023.11 | 153.5 | 150.2 | 105.4 | (125.2 projected, +0.4) | 12.20 |
| 2023.12 | 151.1 | 146.4 | 114.2 | (121.9 projected, -3.3) | 9.60 |
| 2024.01 | 164.6 | 159.3 | 123.0 | (118.5 projected, -3.4) | 5.46 |
| 2024.02 | 172.5 | 168.3 | 124.7 | (117.7 projected, -0.8) | 5.31 |
| 2024.03 | 154.4 | 152.9 | 104.9 | (117.1 projected, -0.6) | 11.03 |
| 2024.04 | 161.3 | 162.6 | 136.5 | (117.1 projected, -0.0) | 9.5 |
| 2024.05 | 134.8 (1) | 3.4 (2A) / 104 (2B) / 167.3 (2C) | (118.3 projected, +1.2) | (7.6) | |
| 2024.06 | (117.4 projected, -0.9) | ||||
| 2024.07 | (115.7 projected, -1.7) | ||||
| 2024.08 | (113.8 projected, -1.9) | ||||
| 2024.09 | (112.5 projected, -1.3) | ||||
| 2024.10 | (111.1 projected, -1.4) | ||||
| 2024.11 | (108.6 projected, -2.5) | ||||
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
The big increase in sunspot counts during the April 14-27 interval caused a major uptick in the smoothed SNs and solar flux. It's not yet clear when the next peak will be, anytime between October 28 and December 20, 2023 looks possible. The 365d smoothed solar flux exceeded the June 27 peak on October 28, while the 365d smoothed ISN and NOAA SN both exceeded the June 2023 peak in late October 2023. It should be noted that the current peak using 13-month smoothing is still in June 2023.
--------------------------------------------------------------------------------------
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.
