Detailed Information

Solar Activity

Solar activity was eruptive in the last 24 hours, with three C-class flares detected.

There were no M-class or X-class flares observed during this period. The strongest event was a C1.6 flare peaking at 15:14 UT from an unknown region. Associated with this activity, no solar radio bursts were reported. Three coronal mass ejections were observed, with one detected on the western limb propagating at 329 km/s with a 6-degree width, and another on the eastern limb at 445 km/s with a 26-degree width. On the visible disk, two active regions were identified by SDO/HMI: NOAA 14415 and NOAA 14419. Meanwhile, no H-alpha plages were observed by BBSO. Looking at the farside, five regions are expected to return to the visible disk between April 21 and April 23.

For the next 24 hours, solar activity is predicted to be eruptive, with the Random Forest model forecasting a maximum flare class of M.

 

Geomagnetic Activity

The geomagnetic activity was on minor storm level for the last 24 hours.

The solar wind speed increase from 398 km/s and 566 km/s. The north-south component of interplanetary magnetic field decrease from 6.3 nT to -6.9 nT. There was geoeffective coronal hole at western equator, while the others at north pole and south-east were not geoeffective. CME on 21 April 2026 21:00 UT was mainly errupted toward north-east with speed of 445 km/s and angular width of 26°. The CME was not geoeffective and is likely to have not impact on next 24 hours.

Minor Storm level geomagnetic activity is expected for the next 24 hours.

Ionospheric Activity

Ionosfer was in moderate conditions on 24 hours.

There was depression in the foF2 of its median value for 135 minutes in the last 24 hours. There was an increment in fmin exceeding 30% of its median value for 45 minutes in the last 24 hours. There was a Spread-F Event for 165 minutes in the last 24 hours. Sporadic E-layer during the day and night for 570 minutes with foEs values higher than foF2 values in the last 24 hours. The ionospheric scintillation index (S4) above Pontianak was less than 0.5 (quiet) and the maximum TEC value was 77.8 (quiet) both observed above Pontianak.

The ionosphere activity is predicted to be minor for the next 24 hours.

Navigation

The error of the single frequency GPS positioning for the next 24 hours was on normal level, based on ionospheric scintillation and TEC variation.

Based on ionospheric scintillation and TEC variation, the probability of error positioning for the next 24 hours is predicted to be on normal level.

HF Radio Communication

In the last 24 hours, the Maximum Usable Frequency (MUF) Depression was at a strong level, and the Short-Wave Fadeout (SWF) was at a moderate level.

The MUF depression for the next 24 hours is predicted at a minor level, due to previous geomagnetic activity.

The SWF for the next 24 hours is predicted at a quiet level due to the prediction of a solar flare.

Satellites

The electron flux was on high level for the last 24 hours.
Low level of elektron flux is expected for the next 24 hours.

The 10 MeV proton flux was quiet for the last 24 hours.

Based on today's conditions, the flux of high-energy protons for the next 24 hours is predicted to be quiet.