Solar Terrestrial Activity Report

Last major update issued on December 2, 2005 at 05:45 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update November 9, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update November 9, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update November 9, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update November 2, 2005)]

Recent activity

The geomagnetic field was quiet to active on December 1. Solar wind speed ranged between 607 and 768 (all day average 690) km/sec under the influence of a high speed stream from CH200.

Solar flux measured at 20h UTC on 2.8 GHz was 98. The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 12.9)
Three hour interval K indices: 42122224 (planetary), 42232225 (Boulder).

The background x-ray flux is at the class B2 level.

At midnight there were 4 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 6 C class events was recorded during the day. A C2.1 event at 02:38 UTC had a source just behind the northeast limb and was associated with a fast CME over the east limbs. 

Region 10824 decayed and rotated to the southwest limb.
Region 10826 developed quickly and has a strong magnetic delta structure in the large central penumbra. Further major flares are possible, even a low level X class flare. Flares: C1.4 at 00:18, C5.7 at 05:04, C6.0 at 08:37, C1.5 at 12:21 and C2.2 at 15:35 UTC. A major M6.5 flare was observed at 02:52 UTC on December 2.
Region 10827 was quiet and stable.
New region 10828 emerged in the southeast quadrant.

Coronal mass ejections (CMEs)

December 2: The major M6 event in region 10826 early in the day strongly affected the corona to the west and northwest of the region. It is likely that this event was associated with a significant Earth directed CME.
November 30 and December 1
: No obvious fully or partly Earth directed CMEs were observed.
November 29: A partial halo CME was observed over the southern hemisphere and the northwest limb after the C4 LDE in region 10824. The core ejected material was first observed over the southwest limb in LASCO C2 images at 17:30 and in C3 at 18:18 UTC while a more diffuse front appeared soon afterwards over the south pole, the southeast quadrant and some of the northwest quadrant.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

Recurrent trans equatorial coronal hole CH200 was in an Earth facing position on November 28-30.

Processed SOHO/EIT 284 image at 19:06 UTC on December 1. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to minor storm on December 2 due to a high speed stream from CH200. The major event in region 10826 on December 2 may have caused a CME which could reach Earth late on December 3 or on December 4 and cause active to major geomagnetic storming. 

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
Coronal hole indicator CME indicator M and X class flare indicator

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) Material from a CME is likely to impact 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.


Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). Propagation favored Venezuela, but not that many stations were audible. A few of the most common east coast stations from North America were audible at low signal levels.

Active solar regions (Recent map)

Compare to the previous day's image.

Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. 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 SEC or where SEC has observed no spots. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.

Active region Date numbered SEC
Location at midnight Area Classification Comment
10824 2005.11.20 3 1 S14W75 0070 CRO classification was HRX at midnight, area 0020
10825 2005.11.25     S03W62     plage
10826 2005.11.28 22 30 S02E22 0210 EKC beta-gamma-delta
area was 0600 at midnight
location: S04E17
10827 2005.11.30 6 N08E42 0050 DRO classification was DSO at midnight, area 0040
location: N06E41
10828 2005.12.01 8 S04E42 0060 DSO classification was DAO at midnight, area 0090
Total spot count: 39 44  
SSN: 79 84  

Monthly solar cycle data

Month Average solar
flux at Earth
International sunspot number Smoothed sunspot number
2000.04 184.2 125.5 120.8
cycle 23 sunspot max.
2000.07 202.3 170.1 119.8
2001.12 235.1 132.2 114.6 (-0.9)
2004.10 105.9 48.0 35.9 (-1.6)
2004.11 113.2 43.5 35.3 (-0.6)
2004.12 94.5 17.9 35.2 (-0.1)
2005.01 102.2 31.3 34.6 (-0.6)
2005.02 97.2 29.2 33.9 (-0.7)
2005.03 89.9 24.5 33.5 (-0.4)
2005.04 86.0 24.4 31.6 (-1.9)
2005.05 99.3 42.6 28.9 (-2.7)
2005.06 93.7 39.6 (28.1 predicted, -0.8)
2005.07 96.4 39.9 (27.6 predicted, -0.5)
2005.08 90.5 36.4 (25.7 predicted, -1.8)
2005.09 91.1 22.1 (23.6 predicted, -2.1)
2005.10 77.0 8.5 (21.6 predicted, -2.0)
2005.11 86.3 18.0 (19.2 predicted, -2.4)
2005.12 98 (1) 2.5 (2) (16.4 predicted, -2.8)

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC) sunspot number. The official international sunspot number is typically 30-50% lower.

This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.

[DX-Listeners' Club]