The geomagnetic field was unsettled to active on April 27 under the influence of effects from CH1142. Solar wind speed at SOHO ranged between 570 and 707 km/sec. The high latitude magnetometer at Andenes recorded active to major storm levels.
Solar flux density measured at 20h UT on 2.8 GHz was 140.8 - increasing 11.2 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 139.51. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 23 (STAR Ap - based on the mean of three hour interval ap indices: 22.8). Three hour interval K indices: 44334433 (planetary), 45333432 (Boulder), 56444565 (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 14 active regions using 2K resolution (SN: 288) and in 12 active regions using 1K resolution (SN: 195) SDO/HMI images.
Region 13285 [S17W11] decayed slowly and
quietly.
Region 13286 [S11W00] was quiet and stable.
Region 13287 [S25E29] was quiet and stable.
Region 13288 [S22W05] developed further as magnetic delta in the central spot section
enlarged. M class flares are
possible. C1. flares: C1.1 @ 08:53, C1.0 @ 09:21, C1.1 @ 09:44, C1.3 @
10:32, C1.7 @ 16:16, C1.0 @ 18:34, C1.0 @ 22:44 UT
Region 13289 [N19E52] decayed slowly. There is a small magnetic delta in a northern
penumbra. An M class flare is possible. C1 flare: C1.4 @ 19:36 UT
Region 13290 [N25W58] decayed slowly and quietly.
Region 13291 [N09W00] developed slowly and quietly.
New region 13292 [N15E58] rotated into view on April 25 and was
numbered by SWPC 2 days later.
Spotted regions not observed (or interpreted
differently) by SWPC:
S8489 [N18W14] was quiet and stable.
S8492 [N16W25] was quiet and stable.
S8497 [S17E18] was quiet and stable.
New region S8501 [N17E26] emerged with tiny
spots.
New region S8502 [N13W24] emerged with a tiny spot.
New region S8503 [S15W27] emerged with tiny spots.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.7 | 00:04 | 13288 | GOES16 | ||
| C3.0 | 00:59 | 13289 | GOES16 | ||
| C2.5 | 02:49 | 13289 | GOES16 | LDE | |
| M1.8 | 11:14 | S23E04 | 13288 | GOES16 | |
| C2.5 | 19:48 | 13288 | GOES16 | ||
| C2.4 | 23:26 | 13288 | GOES16 |
April 25-26: No obviously Earth directed CMEs were
observed.
April 27: A CME was observed after a filament eruption near AR 13289
early in the day. There's a slight chance effects from this CME could reach
Earth late on April 29 or on April 30.
[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 (CH1142) was Earth facing on April 23-26. A northern hemisphere coronal hole (CH1143) will rotate across the central meridian on April 27-28.
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 active conditions are likely on April 28-29 due to effects from CH1142. On April 30-May 1 quiet to unsettled conditions are likely due to effects from CH1143.
| 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 | ||||||||||
| 13284 | 2023.04.17 2023.04.17 |
S08W67 |
 |
location: S08W64 |
|||||||
| S8475 | 2023.04.19 | N26W59 | |||||||||
| S8479 | 2023.04.20 | N06W54 | |||||||||
| 13285 | 2023.04.20 2023.04.21 |
5 | 19 | 11 | S19W10 | 0240 | CAO | CAO |
 |
 |
location: S17W11 |
| S8482 | 2023.04.21 | S23W53 | |||||||||
| 13286 | 2023.04.21 2023.04.24 |
3 | 18 | 9 | S11W02 | 0010 | BXO | CRO |
 |
 |
area: 0025 |
| S8485 | 2023.04.22 | N16W37 | |||||||||
| S8486 | 2023.04.22 | N27W29 |
 |
||||||||
| 13287 | 2023.04.23 2023.04.24 |
3 | S25E21 | 0003 | BXO |
 |
 |
location: S25E29 | |||
| S8488 | 2023.04.23 | S26W09 | |||||||||
| S8489 | 2023.04.23 | 9 | 2 | N18W14 | 0015 | BXO |
 |
 |
|||
| 13288 | 2023.04.24 2023.04.25 |
29 | 43 | 28 | S23W07 | 0380 | EKI | EKI |
 |
 |
beta-gamma-delta area: 0460 location: S22W05 |
| S8492 | 2023.04.24 | 1 | 1 | N16W25 | 0004 | AXX |
 |
 |
|||
| S8493 | 2023.04.24 | S21W28 |
 |
||||||||
| 13289 | 2023.04.25 2023.04.25 |
5 | 18 | 4 | N20E51 | 0180 | DAO | DAC |
 |
 |
beta-delta location: N19E52 |
| 13290 | 2023.04.25 2023.04.26 |
3 | 2 | 2 | N24W59 | 0010 | BXO | BXO |
 |
 |
area: 0005 |
| 13291 | 2023.04.25 2023.04.26 |
20 | 24 | 13 | N09W02 | 0030 | CRO | DAI |
 |
 |
area : 0110 |
| S8497 | 2023.04.25 | 3 | S17E18 | 0008 | BXO |
 |
 |
||||
| 13292 | 2023.04.25 2023.04.27 |
1 | 1 | 1 | N14E62 | 0010 | HRX | HAX |
 |
 |
area: 0020 |
| S8499 | 2023.04.25 | S27W24 | |||||||||
| S8500 | 2023.04.26 | N12E07 |
 |
||||||||
| S8501 | 2023.04.27 | 2 | 1 | N17E26 | 0005 | BXO |
 |
||||
| S8502 | 2023.04.27 | 1 | 1 | N13W24 | 0003 | AXX |
 |
||||
| S8503 | 2023.04.27 | 4 | 2 | S15W27 | 0008 | BXO |
 |
||||
| Total spot count: | 66 | 148 | 75 | ||||||||
| Sunspot number: | 136 | 288 | 195 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 92 | 181 | 108 | (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): | 150 | 158 | 156 | ||||||||
| 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 | (99.0 projected, +2.6) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | (102.0 projected, +3.0) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | (106.8 projected, +4.8) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 143.6 | (112.9 projected, +6.1) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 110.9 | (117.9 projected, +5.0) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 122.6 | (121.0 projected, +3.1) | 14.42 |
| 2023.04 | 144.5 (1) | 82.3 (2A) / 91.4 (2B) / 137.4 (2C) | (126.4 projected, +5.4) | (13.0) | |
| 2023.05 | (132.1 projected, +5.7) | ||||
| 2023.06 | (135.2 projected, +3.1) | ||||
| 2023.07 | (134.7 projected, -0.5) | ||||
| 2023.08 | (135.7 projected, +1.0) | ||||
| 2023.09 | (139.2 projected, +3.5) | ||||
| 2023.11 | (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.
