The geomagnetic field was quiet on May 4. Solar wind speed at SOHO ranged between 353 and 454 km/s.
Solar flux at 20h UTC on 2.8 GHz was 123.4 (increasing 12.2 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 125.6. The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.8). Three hour interval K indices: 21212211 (planetary), 21320*** (Boulder).
The background x-ray flux is at the class B8 level.
At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 227) and 9 active regions using 1K resolution (SN: 152) SDO images on the visible solar disk.
Region 12335 [S15E24] developed small magnetic
deltas centrally and could produce minor M class flares.
Region 12336 [N13W00] developed slowly and quietly.
Region 12337 [S17E43] developed slowly and was quiet.
Region 12338 [N04E44] developed slowly, has minor polarity intermixing
and could produce further C flares.
Spotted regions not numbered (or interpreted
differently) by SWPC:
S4426 [S12W07] decayed slowly and quietly.
S4429 [S27W03] was quiet and stable.
S4432 [S10W35] reemerged with penumbra spots.
S4439 [N12E62] developed slowly and quietly.
New region S4440 [N12E82] rotated partly into view and is the region most
likely to produce an M class flare.
New region S4441 [N13E35] was observed with a penumbra spot.
New region S4442 [S27E36] was observed with a penumbra spot.
New region S4443 [S03W30] emerged with a penumbra spot.
| Magnitude | Peak time (UTC) | Location | AR | Recorded by | Comment |
| C8.0/1F | 00:52 | S18E42 | 12335 | GOES15 | |
| C3.0 | 03:03 | N05E58 | 12338 | GOES15 | |
| C2.0 | 10:32 | S4440 | GOES15 | ||
| C5.1 | 17:05 | S4440 | GOES15 |
May 3-4: No obviously
Earth directed CMEs were observed.
May 2: A partial halo CME was observed late in the day and early on May 3
after a large filament eruption in the southern hemisphere.
[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 (CH666) was in a potentially geoeffective position on May 2. CH666 has decayed and may not be capable of creating a geomagnetic disturbance. A recurrent extension of the southern polar coronal hole could rotate across the central meridian on May 8-9.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on May 5. There is a slight possibility of a few unsettled intervals due to weak effects from CH666 on May 5-6. The CME observed late on May 2 and early on May 3 was fairly slow and may have had Earth directed extensions which could reach us on May 6. In that case some unsettled and active intervals are possible.
| 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)
Compare to the previous day's 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 numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC. 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.
| Active region | Date numbered detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC | Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 12334 | 2015.04.27 2015.04.30 |
S20W45 | |||||||||
| S4421 | 2015.04.27 | S10W44 | |||||||||
| S4423 | 2015.04.29 | S27W58 | |||||||||
| 12335 | 2015.04.30 | 30 | 51 | 27 | S15E24 | 0310 | EAC | EAC |
 |
 |
beta-gamma-delta area: 0500 |
| S4426 | 2015.04.30 | 5 | 4 | S12W07 | 0015 | BXO |
 |
 |
|||
| S4427 | 2015.04.30 | N13W57 | |||||||||
| S4428 | 2015.04.30 | N13W29 | |||||||||
| S4429 | 2015.05.01 | 2 | 1 | S27W03 | 0007 | AXX |
 |
 |
|||
| S4430 | 2015.05.01 | S22W58 | |||||||||
| S4431 | 2015.05.02 | N01W51 | |||||||||
| S4432 | 2015.05.02 | 2 | 1 | S10W35 |
 |
||||||
| 12338 | 2015.05.02 2015.05.03 |
4 | 14 | 9 | N04E42 | 0020 | BXO | DRI |
 |
 |
area: 0100 |
| 12336 | 2015.05.02 2015.05.03 |
9 | 20 | 13 | N13W00 | 0030 | DRO | DRI |
 |
 |
area: 0070 |
| 12337 | 2015.05.02 2015.05.03 |
2 | 4 | 3 | S16E42 | 0010 | BXO | DRO |
 |
 |
area: 0020 |
| S4437 | 2015.05.02 | N10W29 | |||||||||
| S4438 | 2015.05.03 | N05E53 |
 |
||||||||
| S4439 | 2015.05.03 | 3 | 2 | N12E62 | 0013 | CRO |
 |
 |
|||
| S4440 | 2015.05.03 | 3 | 2 | N12E82 | 0200 | HAX |
 |
||||
| S4441 | 2015.05.04 | 1 | N13E35 | 0002 | AXX |
 |
|||||
| S4442 | 2015.05.04 | 1 | S27E36 | 0002 | AXX |
 |
|||||
| S4443 | 2015.05.04 | 1 | S03W30 | 0001 | AXX |
 |
|||||
| Total spot count: | 45 | 107 | 62 | ||||||||
| Sunspot number: | 85 | 227 | 152 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 53 | 129 | 84 | (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): | 51 | 79 | 84 | k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number) | |||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number | Average
ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2013.12 | 147.7 | 143.1 | 90.3 | 76.0 (+0.6) | 4.68 |
| 2014.01 | 157.4 | 152.4 | 81.8 | 77.3 (+1.3) | 5.44 |
| 2014.02 | 170.3 (cycle peak) |
166.3 | 102.3 (cycle peak) | 78.4 (+1.1) | 10.70 |
| 2014.03 | 149.9 | 148.5 | 91.9 | 80.8 (+2.4) | 4.88 |
| 2014.04 | 143.9 | 144.8 | 84.7 | 81.9 (+1.1) (solar max) | 7.88 |
| 2014.05 | 129.7 | 132.9 | 75.2 | 80.5 (-1.4) | 5.75 |
| 2014.06 | 122.0 | 125.8 | 71.0 | 79.7 (-0.8) | 6.72 |
| 2014.07 | 137.4 | 141.8 | 72.5 | 78.5 (-1.2) | 4.50 |
| 2014.08 | 124.7 | 127.9 | 74.7 | 75.5 (-3.0) | 7.71 |
| 2014.09 | 146.6 | 148.1 | 87.6 | 70.8 (-4.7) | 9.78 |
| 2014.10 | 153.4 | 152.9 | 60.6 | 67.3 (-3.5) | 8.96 |
| 2014.11 | 154.8 | 151.4 | 70.1 | (64.9 projected, -2.4) | 9.33 |
| 2014.12 | 158.7 | 153.8 | 78.0 | (62.6 projected, -2.3) | 11.24 |
| 2015.01 | 141.9 | 137.3 | 67.0 | (60.4 projected, -2.2) | 9.46 |
| 2015.02 | 129.1 | 126.0 | 44.8 | (58.7 projected, -1.7) | 9.92 |
| 2015.03 | 125.9 | 124.6 | 38.4 | (56.3 projected, -2.4) | 16.14 |
| 2015.04 | 128.8 | 129.7 | 54.4 | (53.7 projected, -2.6) | 10.3 |
| 2015.05 | (110.0) | 6.1 (2A) / 47.5 (2B) / 78.8 (2C) | (51.5 projected, -2.2) | (5.7) | |
1) Running average based on the daily 20:00 UTC observed solar flux value at
2800 MHz.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC)
sunspot number (accumulated daily sunspots / month days). The official WDC-SILSO
international sunspot number is typically 30-50% lower. 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.
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 the UTC day. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
