Solar Terrestrial Activity Report

Last major update issued on June 28, 2005 at 04:10 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 21, 2005)]

Recent activity

The geomagnetic field was inactive to quiet on June 27. Solar wind speed ranged between 362 and 471 (all day average 419) km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 77.4. The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.4).
Three hour interval K indices: 10012221 (planetary), 11012223 (Boulder).

The background x-ray flux is at the class A5 level.

At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was low. A single C class event was recorded during the day.

New region 10781 rotated into view at the northeast limb. While this region has been quite active over the last several days, activity appeared to be diminishing late on June 27 and early on June 28. Flare: C2.8 at 08:48 UTC.

Spotted regions not numbered by NOAA/SEC:
[S562] This region emerged in the southwest quadrant on June 27 with two tiny spots. Location at midnight: S15W19.
[S563] A new region emerged in the northeast quadrant on June 27. Location at midnight: N10E35.

Coronal mass ejections (CMEs)

June 25: A full halo CME was observed in LASCO C3 images beginning at 08:42 UTC. While quite a bit of coronal activity was observed in the central southeast quadrant during the first half of the day, the timing of the CME makes it likely that its source was backsided. 
June 26: A symmetric full halo CME was observed in LASCO C3 images beginning at 08:18 UTC. No relevant activity was observed on the visible disk during the hours before this observation, thus the source of the CME was most likely backsided.
June 27: No obvious fully or partly Earth directed CMEs were observed in available 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

A coronal hole (CH172) in the southern hemisphere (and with a trans equatorial extension) was in an Earth facing position on June 24-25. A large trans equatorial coronal hole (CH173) will likely be in an Earth facing position on June 28-30.

Processed SOHO/EIT 284 image at 01:06 UTC on June 28. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on June 28 due to a low speed stream from CH172. Quiet to unsettled is likely on June 29-30 while a high speed stream from CH173 is likely to arrive on July 1 and cause unsettled to minor storm conditions that day and on July 2-3.

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 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. Radio Real (Uruguay) on 1590 had a good signal as well and fair signals were noted from Brazilian stations on 930 and 1540 kHz. Unfortunately heavy thunderstorm activity over the English Channel and the Bay of Biscay prevented any weak signals from becoming 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
10780 2005.06.17     S07W69     plage
10781 2005.06.27 1 2 N16E76 0060 HSX classification was HAX at midnight
S562 2005.06.27   2 S15W19 0000 BXO  
S563 2005.06.27   1 N10E35 0000 AXX  
Total spot count: 1 5  
SSN: 11 35  

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 94.1 (1) 54.0 (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% 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]