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91-10-17.DLY
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1991-10-17
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/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
DAILY SUMMARY OF SOLAR GEOPHYSICAL ACTIVITY
17 OCTOBER, 1991
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
(Based In-Part On SESC Observational Data)
SOLAR AND GEOPHYSICAL ACTIVITY INDICES FOR 17 OCTOBER
-----------------------------------------------------
!!BEGIN!! (1.0) S.T.D. Solar Geophysical Data Broadcast for DAY 290, 10/17/91
10.7 FLUX=169.4 90-AVG=198 SSN=166 BKI=1111 3211 BAI=005
BGND-XRAY=B6.5 FLU1=1.1E+06 FLU10=6.5E+03 PKI=1112 2222 PAI=006
BOU-DEV=005,008,008,009,029,011,006,009 DEV-AVG=010 NT SWF=00:000
XRAY-MAX= C1.8 @ 0519UT XRAY-MIN= B6.2 @ 0812UT XRAY-AVG= B9.3
NEUTN-MAX= +004% @ 0600UT NEUTN-MIN= -004% @ 0750UT NEUTN-AVG= +0.0%
PCA-MAX= +0.3DB @ 2300UT PCA-MIN= -5.0DB @ 1225UT PCA-AVG= -0.3DB
BOUTF-MAX=55316NT @ 1357UT BOUTF-MIN=55271NT @ 1828UT BOUTF-AVG=55294NT
GOES7-MAX=P:+183NT@ 1832UT GOES7-MIN=N:+001NT@ 2357UT G7-AVG=+109,+031,+007
GOES6-MAX=P:+180NT@ 1835UT GOES6-MIN=E:-020NT@ 0639UT G6-AVG=+118,-009,+024
FLUXFCST=STD:168,167,167;SESC:170,170,170 BAI/PAI-FCST=007,007,015/010,015,025
KFCST=2233 3222 2233 3222 27DAY-AP=007,007 27DAY-KP=2222 2221 1112 3322
WARNINGS=*MAJFLR
ALERTS=**MAGSI:7NT@1330UT
!!END-DATA!!
BRIEF SUMMARY OF EVENTS
-----------------------
Solar activity was low today. Only three small C-class subflares were
observed during the UT day. Amazingly, the largest x-ray burst was a class
C1.8 event at 05:19 UT from Region 6873 (S22W45). This region displayed
gradual decay today. It is still capable of producing M-class flares with a
very slight risk for a major event. However, the decay which has taken place
over the last 24 hours has been sufficient to terminate the proton and PCA
warnings which were issued yesterday. We no longer anticipate a major event
from this region before it departs the west limb in several more days,
although we do acknowledge a slight risk for a major event should the region
destabilize as it continues to decay. Most of the activity should remain
within the C or minor M-class range.
No new solar regions were numbered today. All of the other regions
visible were quiet.
Geomagnetic activity has been quiet. A sudden magnetic impulse
measuring only 7 nanotesla (nT) was observed at Boulder at 13:30 UT. Other
middle latitude stations also recorded this small magnetic event, as did
geosynchronous spacecraft. The source is unknown. Despite this event,
activity remained mostly quiet to perhaps sporadically unsettled throughout
the day. Conditions should remain quiet to unsettled over the next 48 hours.
Very recent imagery indicates a possible coronal hole west of a coronal
extension to north solar latitude 17 degrees. Unfortunately, the weekly STFR
was compiled prior to this observation. As a result, the forecasts given in
the STFR may be late by one day, if this coronal development persists. In
other words, a modest increase in activity may occur on 20 or 21 October. We
are nearing the end of the quiet interval for this solar rotation.
HF propagation conditions have been normal to above normal throughout
the UT day. Conditions should remain normal to above normal for the next 48
hours, becoming mostly normal by 20 or 21 October. Thereafter, conditions
should gradually deteriorate as coronal-induced activity enhances geomagnetic
and auroral activity.
** End of Daily Update **