Solar Terrestrial Activity Report

Last major update issued on June 12, 2005 at 04:25 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 4, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 4, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 4, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update June 4, 2005)]

Recent activity

The geomagnetic field was very quiet to unsettled on June 11. Solar wind speed ranged between 284 and 329 km/sec. Solar wind density increased slowly after 15h UTC, however, no increase in solar wind speed has been observed as I write this.

Solar flux measured at 20h UTC on 2.8 GHz was 108.0. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.4).
Three hour interval K indices: 21111223 (planetary), 21112223 (Boulder).

The background x-ray flux is at the class B1 level.

At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

Region 10773 decayed slowly and quietly.
Region 10775 developed as new spots emerged near the main penumbra. There could be a weak magnetic delta structure in a small penumbra near the northeastern part of the large spot. This region was the source of a long duration C3.5 event early on June 12.
Region 10776 decayed in the trailing spot section with penumbral coverage decreasing. The region could still produce a minor M class flare.

Coronal mass ejections (CMEs)

June 10-11: No obvious fully or partly Earth directed CMEs were observed in LASCO images.
June 9: A faint full halo CME was observed in LASCO C3 images during the late afternoon and early evening and may have been related to a long duration low level x-ray enhancement.
June 8: At least a partial halo CME was observed in LASCO C3 images during the late afternoon and early evening. The ejected material was first observed over the southwest limb and was likely related to a filament eruption to the north of region 10772.

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

No obvious coronal holes are currently near Earth facing positions.

Processed SOHO/EIT 284 image at 01:06 UTC on June 6. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on  June 12-13 and quiet to unsettled on June 14-15.

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 to very poor. Propagation along long distance north-south paths is poor to very poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Vibración (Venezuela), both with weak signals. Only a few other trans Atlantic signals were audible.

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
10773 2005.06.01 3 2 S15W54 0060 CSO classification was HAX at midnight, area 0040
10775 2005.06.04 13 28 N10W19 0330 DKI beta-gamma
classification was DKC at midnight, area 0410
10776 2005.06.05 28 39 S06W08 0520 EKI beta-gamma
area was 0470 at midnight
10777 2005.06.10 1   N05E41 0010 AXX spotless
S555 2005.06.07     S03W54     plage
S556 2005.06.09     N05W21     plage
Total spot count: 45 69  
SSN: 85 99  

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)
2004.04 101.2 39.3 45.5 (-1.6)
2004.05 99.8 41.5 43.8 (-1.7)
2004.06 97.4 43.2 41.6 (-2.2)
2004.07 119.1 51.1 40.2 (-1.4)
2004.08 109.6 40.9 39.2 (-1.0)
2004.09 103.1 27.7 37.5 (-1.7)
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 (34.8 predicted, -0.5)
2005.01 102.2 31.3 (32.8 predicted, -2.0)
2005.02 97.2 29.1 (30.4 predicted, -2.4)
2005.03 89.9 24.8 (28.8 predicted, -1.6)
2005.04 86.0 24.4 (26.9 predicted, -1.9)
2005.05 99.3 42.6 (24.3 predicted, -2.6)
2005.06 105.1 (1) 31.3 (2) (22.8 predicted, -1.5)

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% less.

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]