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Product: Daily Forecast of Geomagnetic Activity
Issued: 2026 September 26 08:48UTC
Prepared by the Athens Space Weather Forecasting Center
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I. Solar activity
--Current Status
Solar Flux (10.7cm) measured on 25.09.2026 at 23:00 UTC was 105 sfu.
The background X-Ray flux is at the class B2.1 level.
No obviously Earth directed CMEs were observed in available LASCO imagery on September 22-24.
A coronal hole (CH1400) at southern hemisphere was Earth facing on September 20.
A coronal hole (CH1401) at northern hemisphere rotated across the central meridian on September 22-23.

II. Solar Energetic Particle Events
Protons and electrons fluxes are quiet.

III. Interplanetary and Geomagnetic conditions
The solar wind speed measured by ACE satellite reached the max value 558 Km/s on September 25 at 17:49 UT during the last 24 hours.
The solar wind speed from STEREO A was detected 400 Km/s during the last 24 hours.
The vertical component of IMF Bz reached the max value -8.16 nT on September 25 at 09:43 UT during the last 24 hours.
The geomagnetic field was at quiet to active levels during the last 24 hours.
The Kp index now is at active levels with Kp=4.

IV. 3-day Geomagnetic Activity Forecast
The geomagnetic field is expected to be at quiet to active levels on September 26, at quiet to unsettled levels on September 27 and at quiet levels on September 28.

DateAp index forecastGeomagnetic Activity level
26.09.202612Quiet to Active
27.09.202610Quiet to Unsettled
28.09.202605Quiet

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Athens Space Weather Forecasting Center
Physics Department, National & Kapodistrian University of Athens
Athens Neutron Monitor Station A.NE.MO.S
Tel.: +30 210 727 6901
email: spaceweather@phys.uoa.gr
URL: http://spaceweather.phys.uoa.gr
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