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Product: Daily Forecast of Geomagnetic Activity
Issued: 2025 September 16 03:59UTC
Prepared by the Athens Space Weather Forecasting Center
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I. Solar activity
--Current Status
Solar Flux (10.7cm) measured on 15.09.2025 at 23:00 UTC was 130 sfu.
The background X-Ray flux is at the class B9.9 level.
No obviously Earth directed CMEs were observed in available LASCO imagery on September 12-14.
A large equatorial coronal hole (CH1316) rotated across the central meridian on September 10-13.

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 803 Km/s on September 16 at 00:20 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 -16 nT on September 14 at 2325 UT during the last 24 hours.
The geomagnetic field was at active to strong storm (G3) levels during the last 24 hours.
The Kp index now is at minor storm (G1) levels with Kp=5.

IV. 3-day Geomagnetic Activity Forecast
The geomagnetic field is expected to be at quiet to minor storm (G1) levels on September 16 due to effects from CH1316 and at quiet to unsettled levels on September 17-18.

DateAp index forecastGeomagnetic Activity level
16.09.202520Quiet to Minor storm (G1)
17.09.202512Quiet to Unsettled
18.09.202508Quiet 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
URL: http://spaceweather.phys.uoa.gr
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