Last major update issued on May 13, 2013 at 05:35 UTC.
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May 12, 2013]
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The geomagnetic field was quiet on May 12. Solar wind speed at SOHO ranged between 321 and 418 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 147.3 (increasing 34.0 over the last solar rotation). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.5). Three hour interval K indices: 12110101 (planetary), 23111212 (Boulder).
The background x-ray flux was at the class C1 level.
At midnight UTC the visible solar disk had 13 spotted active regions (in 2K resolution SDO images).
Region 11738 [N16W57] decayed slowly and quietly.
Region 11739 [N12W49] decayed slowly and quietly.
Region 11740 [S21W40] was quiet and stable.
Region 11741 [S22W17] was quiet and stable
Region 11742 [N29E08] decayed slowly and quietly.
Region 11743 [N21E15] developed significantly and could produce at least
C flares.
Region 11744 [N04E30] developed further and could produce further C class
flaring.
Region 11745 [N13E53] gained many spots in the southwestern part. No
umbra was observed on positive polarity spots. C and M class flaring is possible.
Region 11746 [S27E53] became more stable, C and minor M class flares are
possible.
New region 11747 [S18E49] emerged with several spots.
Spotted regions not numbered by SWPC:
New region S2411 [S23E64] emerged with penumbra spots.
New region S2412 [S44E27] emerged with a high latitude penumbra spot.
New region S2413 [N18E49] emerged to the north of ARs 11739 and 11738.
A very active region is currently at the northeast limb. It produced the 2 notable events of the day, an M1.9 long duration event peaking at 20:32 and an impulsive M1.2 flare at 22:44 UTC. More importantly, a major X1.7 long duration event peaking at 02:17 on May 13. Material movement was observed a long distance from the flare center and extended well into the visible disk. A very wide CME was observed in STEREO imagery with STEREO-A observing this as a full halo CME. Whether any parts of the CME are Earth directed is awaiting further analysis.
May 10-12: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
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 poorly defined trans equatorial coronal hole (CH569) was in an Earth facing position on May 9-10.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on May 13-15 with a chance of unsettled intervals on May 13 due to possible effects from CH569.
| 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: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.
(Click on image for 2K 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 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 overlay |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC | STAR SDO | SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 11738 | 2013.05.03 | 4 | 3 | 1 | N17W59 | 0010 | BXO | BXO |
 |
 |
|
| 11739 | 2013.05.03 | 1 | 3 | N11W53 | 0000 | AXX | BXO |
 |
 |
location: N12W49 area: 0006 |
|
| 11740 | 2013.05.03 | 1 | 1 | 1 | S21W39 | 0010 | AXX | AXX |
 |
 |
|
| 11741 | 2013.05.05 2013.05.06 |
9 | 18 | 7 | S23W18 | 0030 | CAO | DRO |
 |
 |
|
| 11742 | 2013.05.07 2013.05.09 |
5 | 6 | 3 | N30E10 | 0050 | CAO | CAO |
 |
 |
location: N29E08 |
| 11743 | 2013.05.08 2013.05.09 |
10 | 23 | 11 | N24E15 | 0110 | DAO | DAI |
 |
 |
beta-gamma location: N21E15 area: 0200 |
| 11744 | 2013.05.08 2013.05.09 |
13 | 51 | 17 | N05E28 | 0190 | DAI | DAI |
 |
 |
beta-gamma location: N04E30 |
| S2406 | 2013.05.08 | N12W18 |
 |
plage | |||||||
| 11745 | 2013.05.10 | 15 | 39 | 18 | N14E51 | 0600 | CKI | EKC |
 |
 |
beta-gamma location: N13E67 |
| 11746 | 2013.05.10 2013.05.11 |
11 | 18 | 7 | S27E53 | 0270 | DHI | DAC |
 |
 |
|
| S2408 | 2013.05.10 | S05W24 |
 |
plage | |||||||
| S2410 | 2013.05.11 | N08W11 |
 |
plage | |||||||
| 11747 | 2013.05.12 | 4 | 6 | 3 | S18E48 | 0010 | BXO | CRO |
 |
area: 0030 | |
| S2411 | 2013.05.12 | 6 | 3 | S23E64 | 0020 | BXO |
 |
||||
| S2412 | 2013.05.12 | 1 | S44E27 | 0002 | AXX |
 |
|||||
| S2413 | 2013.05.12 | 10 | 3 | N18W49 | 0025 | BXO |
 |
||||
| Total spot count: | 73 | 175 | 74 | ||||||||
| Sunspot number: | 173 | 305 | 184 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 113 | 211 | 110 | (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): | 104 | 107 | 101 | k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K | |||||||
| Month | Average measured solar flux | International sunspot number (SIDC) | Smoothed sunspot number | Average ap (3) |
|---|---|---|---|---|
| 2011.11 | 153.5 (cycle max) | 96.7 (cycle max) | 61.1 (+1.2) | 5.55 |
| 2012.02 | 106.5 | 32.9 | 66.9 (+1.4) possible cycle 24 max |
8.81 |
| 2012.03 | 114.7 | 64.3 | 66.8 (-0.1) | 16.08 |
| 2012.04 | 113.0 | 55.2 | 64.6 (-2.2) | 10.10 |
| 2012.05 | 121.5 | 69.0 | 61.7 (-2.9) | 7.06 |
| 2012.06 | 119.6 | 64.5 | 58.9 (-2.8) | 10.08 |
| 2012.07 | 133.9 | 66.5 | 57.7 (-1.2) | 13.90 |
| 2012.08 | 115.4 | 63.0 | 58.1 (+0.4) | 7.96 |
| 2012.09 | 122.9 | 61.4 | 58.1 (-0.0) | 8.07 |
| 2012.10 | 123.3 | 53.3 | 58.6 (+0.5) | 9.97 |
| 2012.11 | 121.3 | 61.8 | (59.1 projected, +0.5) | 7.08 |
| 2012.12 | 108.6 | 40.8 | (58.4 projected, -0.7) | 3.44 |
| 2013.01 | 127.1 | 62.9 | (58.0 projected, -0.4) | 4.69 |
| 2013.02 | 104.3 | 38.0 | (58.2 projected, +0.5) | 6.11 |
| 2013.03 | 111.3 | 57.9 | (57.8 projected, -0.4) | 10.56 |
| 2013.04 | 124.8 | 72.4 | (57.4 projected, -0.4) | 5.40 |
| 2013.05 | 138.2 (1) | 52.7 (2A) / 136.3 (2B) / 72.3 (2C) | (57.5 projected, +0.1) | (7.29) |
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 SIDC 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 Potsdam
WDC
ap indices.
This report has been prepared by Jan Alvestad. It is based on 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.
