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91-09-29.DLY
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1991-09-29
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DAILY SUMMARY OF SOLAR GEOPHYSICAL ACTIVITY
29 SEPTEMBER, 1991
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
(Based In-Part On SESC Observational Data)
SOLAR AND GEOPHYSICAL ACTIVITY INDICES FOR 29 SEPTEMBER
-------------------------------------------------------
!!BEGIN!! (1.0) S.T.D. Solar Geophysical Data Broadcast for DAY 272, 09/29/91
10.7 FLUX=194.7 90-AVG=201 SSN=205 BKI=3213 3333 BAI=012
BGND-XRAY=C1.3 FLU1=4.9E+05 FLU10=9.2E+03 PKI=2213 4433 PAI=013
BOU-DEV=024,013,009,033,031,033,021,025 DEV-AVG=023 NT SWF=01:085
XRAY-MAX= M7.3 @ 1533UT XRAY-MIN= C1.0 @ 2359UT XRAY-AVG= C4.4
NEUTN-MAX= +004% @ 0250UT NEUTN-MIN= -002% @ 0105UT NEUTN-AVG= +0.4%
PCA-MAX= +0.4DB @ 1425UT PCA-MIN= -1.2DB @ 1540UT PCA-AVG= +0.2DB
BOUTF-MAX=55313NT @ 2325UT BOUTF-MIN=55264NT @ 1648UT BOUTF-AVG=55296NT
GOES7-MAX=P:+115NT@ 1647UT GOES7-MIN=N:-005NT@ 0020UT G7-AVG=+082,+054,+005
GOES6-MAX=P:+116NT@ 1859UT GOES6-MIN=E:-017NT@ 0703UT G6-AVG=+094,+001,+029
FLUXFCST=STD:190,190,185;SESC:190,185,180 BAI/PAI-FCST=020,020,025/020,020,030
KFCST=3344 5433 3445 4333 27DAY-AP=021,015 27DAY-KP=1344 4333 3343 3222
WARNINGS=*MAJFLR;*PROTFLR;*PROTON;*PCA;*AURMIDWCH
ALERTS=**MAJFLR:M7.3/4B,S21E30(6853),1512-1533-1642,IV=3@1523;
**TENFLR:630SFU@1513,DUR:53MIN;**245STRM:0000-2400UT
!!END-DATA!!
BRIEF SUMMARY OF EVENTS
-----------------------
Solar activity became high today with the impressive eruption of a large
energetic flare from Region 6853 (S19E28). This event was accompanied by a
long-lived Type IV sweep frequency event at 15:33 UT, contrary to the earlier
preliminary report issued several hours after the event. This flare was
rated a class M7.3/4B event (not a 2N as the preliminary report stated) and
was associated with a 630 sfu tenflare (still preliminary) at 15:13 UT. No
Type II was observed with this flare.
This major energetic event produced point brightenings in nearby Region
6850 (S11E19) which were most likely secondary effects of the large explosion
within 6853. We have impressive full-disk and close-up H-alpha images of
this major solar flare in GIF format on the STD BBS, as well as special high
resolution close-up magnetogram images of Regions 6850, 6853 and 6848.
Region 6853 experienced additional growth today in both white light and
in H-alpha, while Region 6850 remained fairly quiet with only a few minor
C-class events observed. Region 6850 is still the most dominant and complex
group visible on the disk and continues to have the potential for strong
energetic activity. However, the configuration of this group has been
unchanged over the last 24 to 48 hours.
Region 6855 (N18E46) was quiet today, but remained bright in H-alpha and
experienced some growth.
Solar activity should remain low to moderate over the next 24 hours.
Further major flaring is a definite possibility from Region 6853 or 6850,
although no major events are anticipated over the next 24 hours. Regions
6850 and 6853 are the most threatening regions on the disk capable of minor
M-class flares and/or major M or X-class events.
Geomagnetic activity was mostly unsettled to active today. The field is
expected to become active with possible periods of minor (to brief major)
storming over the next 72 hours. A well placed coronal hole combined with
several filament disappearances and todays major solar flare are expected to
generate the activity. The most intense period of activity is expected on 02
October when possible effects from todays large solar flare combine to
enhance geomagnetic activity.
Auroral activity became much quieter today as geomagnetic activity
dropped to more dormant levels. This is not expected to last long, however.
By the end of the UT day on 30 September, auroral activity should be elevated
back up to moderate levels over the high and northerly middle latitude
regions. On 02 October, there is a chance for a fairly substantial increase
in activity and a notable equatorward migration of the auroral oval as we
experience effects from todays major flare. If an impact from this major
event materializes, it could possibly produce a fairly strong and energetic
auroral display.
HF propagation conditions were normal to below normal in some regions.
There was a notable increase in noise over most regions while MUFs remained
slightly depressed. Polar and high latitude regions experienced the worst
propagation, with mostly poor conditions. Middle latitudes experienced
better propagation conditions ranging from poor to good. Low latitudes
experienced mostly good conditions with some fair periods interspersed.
Conditions will not improve much over the next 24 hours. In fact, some
additional degradation may be observed over some regions (particularly high
and polar latitude regions) as enhancements in geomagnetic and auroral
activity begin to set in. Conditions should be worst on 02 October when
effects from todays major flare arrive. Provided further influential solar
events do not occur (which is somewhat unlikely), HF propagation conditions
should begin to improve by 03 or 04 October.
** End of Daily Update **