[Ips-dsgr] ASWFC Daily Report - 28 September 26 issued 2330 UT on 28 Sep 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Tue Sep 29 09:30:44 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/28 SEPTEMBER 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 28 SEPTEMBER AND FORECAST FOR 29 SEPTEMBER - 01 OCTOBER
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 28 Sep: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 28 Sep: 95/41
1B. SOLAR FORECAST
29 Sep 30 Sep 01 Oct
Activity R0 R0 R0
Fadeouts None expected None expected None expected
10.7cm/SSN 95/41 100/48 100/48
COMMENT: Solar flare activity on UT day 28-Sep was at the R0
level, with no significant flares observed. Active Region 4535
(N13W31, beta-gamma) is the only active sunspot region currently
visible on the solar disk, and has shown decay over the previous
24 hours. Solar flare activity is forecast to remain at R0 over
29-Sep to 01-Oct. S0 solar radiation storm conditions were observed
on 28-Sep, with the proton flux consistent with background values
across the UT day. S0 solar radiation storm conditions are forecast
over 29-Sep to 01-Oct. A filament eruption centred on N15W60
was observed from 28/1308UT in GOES/SUVI 304A imagery. A resultant
low-velocity, west-directed coronal mass ejection (CME) was observed
in SOHO/LASCO coronagraph imagery from 28/1436UT. Modelling of
this event suggests that the bulk of this eruption will pass
ahead and above the Earth. However, part of this event is expected
to impact Earth, with a glancing CME arrival at Earth forecast
on 01-Oct at 2300UT +/-10 hours. The solar wind environment continued
to trend toward ambient conditions on 28-Sep, following a previous
high speed wind stream. The solar wind speed slowly declined
from 360 km/s early in the UT day to currently be at approximately
320 km/s. The interplanetary magnetic field strength (IMF, Bt)
peaked at 4 nT, with the north-south component (Bz) ranging between
-2 and +2 nT over the UT day. The solar wind speed is expected
to remain at ambient levels over 29-30 Sep, with a rise expected
at the end of UT day 01-Oct due to the glancing CME arrival.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 28 Sep: G0
Estimated Indices 28 Sep : A K
Australian Region 1 10001100
Cocos Island 1 01011100
Darwin 2 11101111
Townsville 2 11011111
Learmonth 1 10101110
Alice Springs 1 10001001
Gingin 0 00001100
Canberra 1 01001001
Kennaook Cape Grim 0 10001000
Hobart 0 00001000
Estimated Antarctic Regional K Indices 28 Sep :
Casey 7 23321111
Mawson 11 22111344
Observed Regional daily pc3 Indices 28 Sep :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 0 (Quiet)
Canberra 0 (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 28 Sep : A
Fredericksburg 5
Planetary 5
Observed AFr/Ap Indices 27 Sep : A K
Fredericksburg 8
Planetary 9 4321 1000
2B. MAGNETIC FORECAST
Date Ap Conditions
29 Sep 5 G0
30 Sep 5 G0
01 Oct 10 G0, chance of G1
COMMENT: Geomagnetic conditions in the Australian region were
at the G0 level over UT day 28-Sep, with G0 conditions also reported
in the Antarctic region, and at the planetary level. G0 geomagnetic
conditions are forecast over 29-30 Sep. G0, with a chance of
G1 conditions are forecast on 01-Oct, with a CME arrival expected
late on this day. Most geomagnetic effects associated with the
CME arrival are expected to occur beyond the current forecast
window.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
28 Sep Fair-normal Fair-normal Fair-normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
29 Sep Normal Normal Normal
30 Sep Normal Normal Normal
01 Oct Normal Normal Normal
COMMENT: Global high-frequency (HF) radio propagation conditions
on UT day 28-Sep were fair to normal. Fair conditions were reported
in the North American region during local night hours, and in
the Asian and northern Australian regions during local dusk hours.
Global HF propagation conditions are forecast to be mostly normal
over the period 29-Sep to 01-Oct.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
28 Sep 49
Observed Australian Regional MUFs
Cocos Island Region:
No data available during local day.
No data available during local night.
Niue Island Region:
Near predicted monthly values during local day.
Depressed by 20% during local night.
Northern Australian Region:
Depressed by 15% during local day.
Near predicted monthly values during local night.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values 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
29 Sep 55 Near predicted monthly values
30 Sep 55 Near predicted monthly values
01 Oct 55 Near predicted monthly values
COMMENT: Maximum Usable Frequencies (MUFs) were mostly near predicted
values in the Southern Australian and Antarctic regions on UT
28-Sep. Depressions of 15% were observed in the Northern Australian
region during local daylight hours, with depressions also observed
at local dawn. Depressions of 20% were also observed at Niue
Island. Mild spread-F was observed in Hobart. MUFs are forecast
to be near predicted values over the period 29-Sep to 01-Oct.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 27 Sep
Daily Proton Fluence >1 MeV: 3.3E+05
Daily Proton Fluence >10 MeV: 2.3E+04
Daily Electron Fluence >2 MeV: 1.30E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:12%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B4.1
Solar Wind Day Averaged Data for 27 Sep
Speed: 406 km/sec Density: 1.8 p/cc Temp: 91700 K Bz: -1 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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