The geomagnetic field was very quiet on April 12. Solar wind speed at SOHO ranged between 354 and 401 km/sec. The high latitude magnetometer at Andenes recorded quiet levels.
Solar flux density measured at 20h UT on 2.8 GHz was 154.0 - increasing 18.6 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 139.16). The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.5). Three hour interval K indices: 00101101 (planetary), 01211221 (Boulder), 00002200 (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 13 active regions using 2K resolution (SN: 328) and in 12 active regions using 1K resolution (SN: 222) SDO/HMI images.
Region 13272 [S20W03] decayed slowly and was
much less active than during the previous days. The region has many small
spots and polarity
intermixing. C1 flares: C1.3 @ 00:17, C1.0 @ 04:24, C1.9 @ 19:16 UT
Region 13273 [N09W14] decayed slowly and quietly.
Region 13274 [S07W29] was quiet and stable.
Region 13275 [N19E37] was quiet and stable.
Region 13276 [S22E47] decayed slowly and quietly.
Region 13277 [N10E08] decayed slowly and quietly.
New region 13278 [N13W33] emerged on April 8 and was numbered by SWPC
4 days later.
New region 13279 [S20E62] rotated into view on April 10 (with SWPC
splitting it off from AR 13276 on April 12). The region has M flare
potential. C1 flares: C1.0 @ 02:51, C1.7 @ 18:18, C1.4 @ 21:55, C1.9 @
22:29, C1.8 @ 23:03, C1.9 @ 23:11 UT
Spotted regions not observed (or interpreted
differently) by SWPC:
S8439 [S29W32] was quiet and stable.
S8445 [N24E05] was quiet and stable.
S8459 [N09E17] decayed slowly and quietly.
S8460 [S09W13] developed slowly and quietly. The region has minor
polarity intermixing and C flares are possible.
New region S8461 [S23E82] rotated into view and may be capable of M
class flaring. C1 flares: C1.5 @ 08:23, C1.6 @ 13:36, C1.4 @ 17:24, C1.4 @
21:20 UT
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.8 | 05:02 | 13279 | GOES18 | ||
| C3.4 | 08:42 | S20E69 | 13279 | GOES16 | |
| C6.1 | 11:53 | S20E70 | 13279 | GOES16 | |
| C2.3 | 15:03 | S8461 | GOES16 | ||
| C5.2 | 15:44 | ? | GOES16 | ||
| C4.8 | 23:35 | 13279 | GOES16 |
April 11: No obviously Earth directed CMEs were
observed.
April 10: A filament eruption in the
northeast quadrant began just after 06h UT and lasted until after 09h UT.
Coronal dimming was observed over a fairly large area to the south of the
eruption. Due to the absence of LASCO imagery for the hours after the event,
it is uncertain if a CME was produced.
April 9: A filament eruption in the
southwest quadrant was observed beginning in SDO/AIA imagery at 19:06 UT and
peaked 40 minutes later. A partial halo CME was observed in LASCO C2 imagery
from 20:00 UT. There is a chance components of this CME will reach Earth on
April 12 or 13.
[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]
While there are a couple of positive polarity coronal holes near the central meridian, they are both likely to be too far north and south to cause a geomagnetic disturbance.
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.
Quiet conditions are likely on April 13-15. There's a chance components of the April 9 and 10 CMEs could reach Earth on April 13-14 and cause unsettled to minor storm conditions.
| 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 | ||||||||||
| S8429 | 2023.04.04 | S19W48 |
 |
||||||||
| 13272 | 2023.04.05 2023.04.06 |
32 | 71 | 42 | S22W02 | 0250 | FKC | FAI |
 |
 |
beta-gamma area: 0230 location: S20W03 |
| S8434 | 2023.04.05 | S07W22 | |||||||||
| S8435 | 2023.04.06 | S27W56 | |||||||||
| S8437 | 2023.04.06 | S13W52 | |||||||||
| S8438 | 2023.04.06 | N14W49 | |||||||||
| S8439 | 2023.04.07 | 4 | 1 | S29W32 | 0008 | BXO |
 |
 |
|||
| 13274 | 2023.04.08 2023.04.10 |
4 | 1 | S07W32 | 0006 | AXX | BXO |
 |
 |
location: S07W29 | |
| 13278 | 2023.04.08 2023.04.12 |
2 | 15 | 7 | N13W34 | 0015 | BXO | CRO |
 |
 |
|
| 13273 | 2023.04.09 2023.04.09 |
11 | 12 | 5 | N10W14 | 0090 | CSO | CAO |
 |
 |
location: N09W14 |
| 13275 | 2023.04.09 2023.04.10 |
1 | 6 | 2 | N19E35 | 0040 | HSX | CAO |
 |
 |
area: 0070 location: N19E37 |
| S8445 | 2023.04.09 | 4 | N24E05 | 0005 | BXO |
 |
 |
||||
| S8446 | 2023.04.09 | N27W15 |
 |
||||||||
| S8447 | 2023.04.09 | S09W06 | |||||||||
| S8448 | 2023.04.09 | N13W52 | |||||||||
| 13276 | 2023.04.10 2023.04.10 |
1 | 3 | 2 | S21E52 | 0020 | HSX | HRX |
 |
 |
area: 0030 location: S22E48 |
| 13277 | 2023.04.10 2023.04.11 |
3 | 10 | 7 | N10E08 | 0020 | BXO | BXO |
 |
 |
|
| S8451 | 2023.04.10 | N29W41 | |||||||||
| 13279 | 2023.04.10 2023.04.12 |
7 | 32 | 16 | S20E60 | 0150 | DAI | EAI |
 |
 |
area: 0260 location: S20E62 |
| S8454 | 2023.04.10 | S01W35 | |||||||||
| S8455 | 2023.04.10 | N23E21 |
 |
||||||||
| S8456 | 2023.04.10 | S09E11 | |||||||||
| S8457 | 2023.04.10 | S33W24 | |||||||||
| S8459 | 2023.04.11 | 4 | 2 | N09E17 | 0010 | BXO |
 |
 |
|||
| S8460 | 2023.04.11 | 27 | 12 | S09W13 | 0090 | DRI |
 |
 |
|||
| S8461 | 2023.04.12 | 6 | 5 | S23E82 | 0330 | DAO |
 |
||||
| Total spot count: | 57 | 198 | 102 | ||||||||
| Sunspot number: | 127 | 328 | 222 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 87 | 232 | 136 | (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): | 140 | 180 | 178 | ||||||||
| 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 | 137.1 (1) | 23.6 (2A) / 59.0 (2B) / 124.0 (2C) | (126.4 projected, +5.4) | (9.0) | |
| 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.
