The above image was taken September 18th at 10:09:00 UTC by the Atmospheric Imaging Assembly (AIA), at 171 Angstroms, aboard the Solar Dynamics Observatory (SDO). This was during the time of a C1 x-ray event, produced by Active Region 1575 (AR 1575) on the eastern (left) limb. Image Credit: SDO/AIA
For the end of September 17th and most of the 18th, the solar activity was at low levels. Newly-designated Active Region 1575 (AR 1575) produced the only C-class flare, which was a C1 x-ray event at on the 18th at 10:09 UTC. This AR was also responsible for the two C-class flares seen yesterday. When AR 1575 rotated onto the Earth-facing disk, it had a beta magnetic classification. No Earth directed coronal mass ejections (CMEs) were detected. The forecast through September 21st: The solar activity is expected to be at low levels with a slight chance for M-class events.
Above Earth, the geomagnetic field has been at quiet to unsettled levels. Solar wind speeds, as measured by the the Advanced Composition Explorer (ACE) spacecraft, indicated nominal background speeds with sustained periods of the negative Bz component of the IMF. The forecast through September 21st: The geomagnetic field is expected to remain at quiet to unsettled levels through the 20th. A slight increase to quiet to unsettled levels with chance for active periods is expected on the 21st as a coronal hole high-speed stream moves into a geoeffective position. Stay tuned...
To monitor solar flare activity minute by minute, visit the "Today's Space Weather" page of NOAA's Space Weather Prediction Center (www.swpc.noaa.gov/today.html).
To learn more about the sun and to stay current on solar activity, visit the mission home pages of the Solar Dynamics Observatory (SDO) (sdo.gsfc.nasa.gov), the Solar and Heliospheric Observatory (SOHO) (sohowww.nascom.nasa.gov), the Advanced Composition Explorer (ACE) (www.srl.caltech.edu/ACE), and the Solar Terrestrial Relations Observatory (STEREO) (stereo.gsfc.nasa.gov).
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