[Ips-dsgr] ASWFC Daily Report - 19 September 26 issued 2330 UT on 19 Sep 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sun Sep 20 09:30:49 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/19 SEPTEMBER 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 19 SEPTEMBER AND FORECAST FOR 20 SEPTEMBER - 22 SEPTEMBER
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 19 Sep: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 19 Sep: 97/44
1B. SOLAR FORECAST
20 Sep 21 Sep 22 Sep
Activity R0 R0, slight chance R1 R0, slight chance R1
Fadeouts None expected None expected None expected
10.7cm/SSN 98/45 98/45 98/45
COMMENT: Solar flare activity on UT day 19-Sep was at the R0
level, with a C3.3 flare peaking at 19/1817UT from the eastern
limb being the largest observed. There are currently three unnumbered
active sunspot regions on the disk, with two small and magnetically
simple regions appearing at N09E05 and S05W37. A third region
has rotated onto the disk at S13E86, and appears to exhibit an
alpha magnetic classification. Solar flare activity is forecast
to be at the R0 level over 20-22 Sep, with a slight chance of
R1 over 21-22 Sep, due to activity on the eastern limb suggesting
a new active region may rotate onto the front side of the disk
in the coming days. S0 solar radiation storm conditions were
observed throughout 19-Sep, with S0 conditions forecast for 20-22
Sep. No geoeffective coronal mass ejections (CMEs) were observed
over the previous UT day. The solar wind environment was stable
over the previous 24 hours, with the solar wind speed ranging
between 400 and 440 km/s throughout the UT day. The interplanetary
magnetic field strength (IMF, Bt) was also stable, peaking at
7 nT, with the north-south component (Bz) ranging between -5
and +5 nT. The solar wind is forecast to remain at this level
over 20-21 Sep, before rising late on 22-Sep as an equatorial
coronal hole begins to move into a geoeffective position.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 19 Sep: G0
Estimated Indices 19 Sep : A K
Australian Region 4 22102211
Cocos Island 3 22111110
Darwin 6 23102212
Townsville 6 23112112
Learmonth 5 22103211
Alice Springs 3 12102111
Gingin 5 22102221
Canberra 3 12101211
Kennaook Cape Grim 4 22102211
Hobart 4 22101211
Estimated Antarctic Regional K Indices 19 Sep :
Casey 12 34422221
Mawson 13 24321333
Observed Regional daily pc3 Indices 19 Sep :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 0 (Quiet)
Canberra 2 (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 19 Sep : A
Fredericksburg 7
Planetary 7
Observed AFr/Ap Indices 18 Sep : A K
Fredericksburg 6
Planetary 5 2222 1112
2B. MAGNETIC FORECAST
Date Ap Conditions
20 Sep 4 G0
21 Sep 4 G0
22 Sep 8 G0
COMMENT: Geomagnetic conditions in the Australian region on UT
day 19-Sep were at the G0 level, with G0 conditions also reported
in the Antarctic region and at the planetary level. G0 conditions
are forecast over 20-22 Sep.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
19 Sep Normal Normal-fair Normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
20 Sep Normal Normal Normal
21 Sep Normal Normal Normal
22 Sep Normal Normal Normal
COMMENT: Global high-frequency (HF) radio propagation conditions
on UT day 19-Sep were mostly normal, with some fair conditions
observed in mid-latitude Asian regions during local night hours.
Global HF propagation conditions are forecast to be mostly normal
over 20-22 Sep.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
19 Sep 60
Observed Australian Regional MUFs
Cocos Island Region:
No data available during local day.
No data available during local night.
Niue Island Region:
Enhanced by 20% during local day.
Near predicted monthly values during local night.
Northern Australian Region:
Mostly near predicted monthly values.
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
20 Sep 60 Near predicted monthly values
21 Sep 60 Near predicted monthly values
22 Sep 60 Near predicted monthly values
COMMENT: Maximum Usable Frequencies (MUFs) in the Australian
region were mostly near predicted values on 19-Sep, with some
enhancements observed at Niue Island. Mild spread-F was observed
in the southern Australian region during local night hours, with
strong spread-F observed at Hobart. MUFs are forecast to remain
near predicted values over 20-22 Sep.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 18 Sep
Daily Proton Fluence >1 MeV: 4.6E+05
Daily Proton Fluence >10 MeV: 2.0E+04
Daily Electron Fluence >2 MeV: 3.80E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 6%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B2.2
Solar Wind Day Averaged Data for 18 Sep
Speed: 424 km/sec Density: 2.8 p/cc Temp: 90100 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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