Last major update issued on May 18, 2005 at 03:05 UTC.
geomagnetic data - last month (updated daily)]
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The geomagnetic field was quiet to active on May 17. Solar wind speed ranged between 448 and 729 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 90.0. The planetary
index was 19 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 44433323 (planetary), 44434323 (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 moderate. A total of 3 C and 1 M class events was recorded during the day.
Region 10759 decayed slowly and quietly.
Region 10763 decayed fairly quickly and lost more than half of its penumbral area. The region simplified and no longer has any magnetic delta structures. Flares: M1.8/1B at 02:39 (associated with a weak type IV and a moderate type II radio sweep), C8.4/1N at 04:03, C2.8 at 05:53 and C1.1 at 23:51 UTC.
Spotted regions not numbered by NOAA/SEC:
[S548] This region emerged in the southeast quadrant on May 17 and was decaying slowly late in the day. Location at midnight: S13E12.
May 15-16: No obviously fully or partly potentially geoeffective CMEs were observed.
May 17: A very faint and slow full halo CME was observed after the M1.8 flare in region 10763 early in the day. This CME could reach Earth early on May 20.
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 recurrent coronal hole (CH166) in the northern hemisphere will likely be in an Earth facing position on May 17. CH166 may be too far to the north to become geoeffective.
Processed SOHO/EIT 284 image at 19:06 UTC on May 17. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected be quiet to unsettled on May 18-19 becoming quiet to active on May 20 due to a weak CME.
|Coronal holes (1)||Coronal mass ejections (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) 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 along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Rafaela (Argentina), both with poor signals. A few North American stations were noted with audio on frequencies above 1400 kHz after 02h UTC, all US frequencies in the range 1620-1700 kHz had moderate to strong carriers.
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|
|10759||2005.05.08||1||2||N11W50||0220||HKX||classification was CKO at midnight, area 0260|
|10763||2005.05.12||24||19||S14W10||0140||EAI||classification was DAI at midnight, area 0080, location: S16W12|
|Total spot count:||25||22|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2004.11||113.2||43.5||(34.8 predicted, -1.1)|
|2004.12||94.5||17.9||(33.4 predicted, -1.4)|
|2005.01||102.2||31.3||(30.9 predicted, -2.5)|
|2005.02||97.2||29.1||(28.3 predicted, -2.6)|
|2005.03||89.9||24.8||(26.5 predicted, -1.8)|
|2005.04||86.0||24.4||(24.6 predicted, -1.9)|
|2005.05||108.8 (1)||42.6 (2)||(22.0 predicted, -2.6)|
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.