[Ips-dsgr] ASWFC Daily Report - 26 September 26 issued 2330 UT on 26 Sep 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sun Sep 27 09:30:50 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/26 SEPTEMBER 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 26 SEPTEMBER AND FORECAST FOR 27 SEPTEMBER - 29 SEPTEMBER
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 26 Sep: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 26 Sep: 101/49
1B. SOLAR FORECAST
27 Sep 28 Sep 29 Sep
Activity R0 R0 R0
Fadeouts None expected None expected None expected
10.7cm/SSN 95/41 95/41 95/41
COMMENT: Solar flare activity on UT day 26-Sep was at the R0
level, with only low-level C-class flares observed. There are
currently six numbered sunspot regions and one unnumbered region
visible on the solar disk. Active region (AR) 4533 and 4539 decayed
over the UT day. ARs 4534, 4537 and 4538 will all rotate off
disk over the next 24 hours. AR3535 (N12W04, beta) has seen growth
in the size and number of trailing spots. The unnumbered region
(S09W55, beta) has remained stable over the UT day, first appearing
on the 25-Sep. All other sunspot regions are either stable or
in decay. Solar flare activity is expected to be at the R0 level
over 27-29 Sep. Solar radiation storm conditions were at the
S0 level on 26-Sep, with the solar proton flux at background
levels. S0 solar radiation storm conditions are forecast over
27-29 Sep. No Earth-directed coronal mass ejections (CMEs) were
observed over the past UT day. The solar wind speed on UT day
26-Sep was largely stable. Speeds ranged from 450 to 510 km/s,
and is currently near 470 km/s. The peak total interplanetary
magnetic field strength (IMF, Bt) was 7 nT. The north-south component
(Bz) ranged between -5 and +6 nT over the same period. Sustained
periods of southward IMF were observed over most of the UT day.
The solar wind speed is expected to decline over 27-29 Sep as
ongoing coronal hole high speed wind stream effects abate.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 26 Sep: G0
Estimated Indices 26 Sep : A K
Australian Region 8 23231122
Cocos Island 3 12120110
Darwin 8 23231122
Townsville 8 23232122
Learmonth 8 22232222
Alice Springs 5 12221122
Gingin 7 22231221
Canberra 7 23231022
Kennaook Cape Grim 8 23232121
Hobart 7 23232012
Estimated Antarctic Regional K Indices 26 Sep :
Casey 11 34331122
Mawson 28 44532236
Observed Regional daily pc3 Indices 26 Sep :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 8 (Quiet)
Canberra 4 (Quiet)
Pc3 pulsations are high frequency (10-45 second period) variations
of the Earths magnetic field. Daily pc3-indices are the daily sum
of 20 minute pc3-indices for that station and have been shown to be
well correlated with rejection of high resolution aeromagnetic
survey flight-line data.
NOTE: Indices may have been generated from data obtained in
cooperation with the following organisations: Geoscience Australia,
University of Newcastle Space Physics Group, Australian Government
Antarctic Division and International Center for Space Weather
Science and Education, Japan.
Estimated AFr/Ap Indices 26 Sep : A
Fredericksburg 13
Planetary 12
Observed AFr/Ap Indices 25 Sep : A K
Fredericksburg 16
Planetary 20 4444 4234
2B. MAGNETIC FORECAST
Date Ap Conditions
27 Sep 12 G0
28 Sep 9 G0
29 Sep 5 G0
COMMENT: G0 geomagnetic conditions were observed in Australia.
One period of G1 and one of G2 geomagnetic conditions were observed
in the Antarctic region at Mawson. Planetary geomagnetic conditions
were at G0. G0 geomagnetic conditions are expected over 27-29
Sep.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
26 Sep Normal Normal-fair Fair-normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
27 Sep Normal Normal Normal-fair
28 Sep Normal Normal Normal-fair
29 Sep Normal Normal Normal
COMMENT: Global high-frequency (HF) radio propagation conditions
on the 26-Sep were degraded at mid to high latitude regions due
to geomagnetic activity from a coronal hole. Global HF conditions
at mid to high latitudes are expected to remain degraded over
most of the 27-Sep, returning to normal conditions on the 28-Sep.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
26 Sep 53
Observed Australian Regional MUFs
Cocos Island Region:
No data available during local day.
No data available during local night.
Niue Island Region:
Enhanced by 15% during local day.
Near predicted monthly values during local night.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Near predicted monthly values during local day.
Depressed by 15% during local night.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 15% over the UT day.
Monthly T index:
Month T index
Aug 66
Sep 62
Oct 60
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
27 Sep 58 Near predicted monthly values
28 Sep 65 Near predicted monthly values
29 Sep 65 Near predicted monthly values
COMMENT: Maximum Usable Frequencies (MUFs) in the Australian
region were mostly near predicted monthly values over UT day
26-Sep with depressions of up to 15% during local night in the
Southern Australian region. Canberra experienced spread-F during
local night. MUFs are forecast to be near predicted monthly values
over 27-29 Sep.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 25 Sep
Daily Proton Fluence >1 MeV: 1.7E+05
Daily Proton Fluence >10 MeV: 2.1E+04
Daily Electron Fluence >2 MeV: 1.40E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 3%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B4.0
Solar Wind Day Averaged Data for 25 Sep
Speed: 486 km/sec Density: 5.5 p/cc Temp: 166000 K Bz: -2 nT
(Courtesy Space Weather Prediction Center, Boulder USA)
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Australian Space Weather Forecasting Centre
Bureau of Meteorology
ASWFC at bom.gov.au
www.bom.gov.au | www.sws.bom.gov.au
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