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Product: Daily Forecast of Geomagnetic Activity
Issued: 2025 September 27 05:51UTC
Prepared by the Athens Space Weather Forecasting Center
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I. Solar activity
--Current Status
Solar Flux (10.7cm) measured on 26.09.2025 at 23:00 UTC was 165 sfu.
The background X-Ray flux is at the class C4.6 level.
An M1.6-class solar flare erupted on September 26 at 20:01 UT peak time producing a radio blackout of category R1.
No obviously Earth directed CMEs were observed in available LASCO imagery on September 23-25.
A small coronal hole (CH1318) at southern hemisphere rotated across the central meridian on September 24.

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 466 Km/s on September 26 at 08:30 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 -4 nT on September 27 at 03:10 UT during the last 24 hours.
The geomagnetic field was at quiet levels during the last 24 hours.
The Kp index now is at quiet levels with Kp=2.

IV. 3-day Geomagnetic Activity Forecast
The geomagnetic field is expected to be at quiet to unsettled levels on September 27-29.

Date	Ap index forecast	Geomagnetic Activity level	
27.09.2025	08	Quiet to Unsettled	
28.09.2025	12	Quiet to Unsettled	
29.09.2025	12	Quiet to Unsettled	

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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
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