Solar Terrestrial Activity Report

Last major update issued on June 8, 2005 at 03:55 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 quiet to minor storm on June 7. Solar wind speed ranged between 431 and 520 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 109.1. The planetary A index was 18 (STAR Ap - based on the mean of three hour interval ap indices: 17.9).
Three hour interval K indices: 45423233 (planetary), 35433223 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight there were 6 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 2 C class events was recorded during the day.

Region 10772 decayed slowly. Flare: C3.0 at 13:42 UTC.
Region 10773 decayed as all intermediate spots disappeared.
Region 10774 decayed slowly and quietly.
Region 10775 added a few small spots near the main penumbra.
Region 10776 developed quickly and became a compact region as many new intermediate spots emerged. By midnight a weak magnetic delta structure had formed in the central part of the region. Further growth will increase the chances of a major flare. Flare: C2.5 at 19:14 UTC.

Spotted regions not numbered by NOAA/SEC:
[S555] This region emerged in the southeast quadrant on June 7 near the central meridian. Location at midnight: S03W01. The region appeared to be decaying late in the day.

Coronal mass ejections (CMEs)

June 5-7: No obvious fully or partly Earth directed CMEs were observed in LASCO images.

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.

Forecast

The geomagnetic field is expected to be quiet to active on June 8 and quiet to unsettled on June 9-10.

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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along long distance north-south paths is fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. At least two stations from Argentina were noted as well. On 1510 kHz Radio Rincón (Uruguay) was best near midnight UTC, later Radio Champaquí (Argentina) dominated before Radio Belgrano (Argentina) became the strongest signal after 03h UTC.

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
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10769 2005.05.28     S06W44     plage
10772 2005.05.31 13 13 S18W44 0130 EAO classification was DAI at midnight
10773 2005.06.01 5 3 S14W04 0130 DAO  
10774 2005.06.04 4 2 N04W45 0040 CAO classification was HAX at midnight, area 0020
10775 2005.06.04 6 11 N10E35 0240 CAO  
10776 2005.06.05 16 26 S06E47 0490 EKO beta-delta
classification was EKC at midnight, area 0570
S555 2005.06.07   1 S03W01 0010 AXX  
Total spot count: 44 56  
SSN: 94 116  

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)
2005.06 100.4 (1) 18.4 (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.


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