From: oler@rho.uleth.ca (Cary Oler)
Newsgroups: sci.space.news
Subject: Daily Summary of Solar Geophysical Activity for 06 April
Date: 7 Apr 92 08:16:42 GMT
Article-I.D.: honte.oler.702634602
Followup-To: sci.space
Organization: University of Lethbridge
Apparently-To: sci-space-news@ames.arc.nasa.gov


                /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

                  DAILY SUMMARY OF SOLAR GEOPHYSICAL ACTIVITY

                                06 APRIL, 1992

                /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

                  (Based In-Part On SESC Observational Data)


SOLAR AND GEOPHYSICAL ACTIVITY INDICES FOR 06 APRIL
---------------------------------------------------

NOTE: The given maximum x-ray flux below was from GOES-6.  GOES-7 was in
      eclipse at the time of maximum.  This event was optically uncorrelated.

!!BEGIN!! (1.0) S.T.D. Solar Geophysical Data Broadcast for DAY 097, 04/06/92
10.7 FLUX=142.7  90-AVG=199        SSN=074      BKI=2663 3322  BAI=028
BGND-XRAY=B6.8     FLU1=1.1E+06  FLU10=1.0E+04  PKI=3553 3332  PAI=025
  BOU-DEV=018,132,142,026,021,029,015,012   DEV-AVG=049 NT     SWF=00:000
 XRAY-MAX= C9.8   @ 0747UT    XRAY-MIN= B5.9   @ 2001UT   XRAY-AVG= B9.5
NEUTN-MAX= +002%  @ 1420UT   NEUTN-MIN= -003%  @ 0450UT  NEUTN-AVG= -0.4%
  PCA-MAX= +0.3DB @ 1355UT     PCA-MIN= -0.1DB @ 1150UT    PCA-AVG= +0.0DB
BOUTF-MAX=55299NT @ 0436UT   BOUTF-MIN=55223NT @ 0703UT  BOUTF-AVG=55269NT
GOES7-MAX=E:+118NT@ 0623UT   GOES7-MIN=N:-043NT@ 0926UT  G7-AVG=+081,+049,+008
GOES6-MAX=P:+125NT@ 2024UT   GOES6-MIN=E:-024NT@ 1956UT  G6-AVG=+091,+008,+033
 FLUXFCST=STD:140,145,145;SESC:140,140,140 BAI/PAI-FCST=012,010,007/015,010,010
    KFCST=2333 3322 2233 3322  27DAY-AP=016,021   27DAY-KP=3323 3334 3435 4332
 WARNINGS=*AURMIDWCH
   ALERTS=
!!END-DATA!!


BRIEF SUMMARY OF EVENTS
-----------------------

     Solar activity continued low.  An optically uncorrelated class C9.8
x-ray event was observed at 07:47 UT by the GOES-6 spacecraft.  At the time
of maximum, GOES-7 (the primary spacecraft) was in eclipse.  The estimated
corrected maximum x-ray flux for this event is approximately C9.5.  A
source for this event does not appear to have been indirectly determined
through analysis of concurrent limb activity.

     Regions 7123 (S06E16) and 7125 (S16E67) both showed minor levels of
growth over the last 24 hours.  Each region also produced minor isolated
subflares throughout the day.

     The National Solar Observatory at Sacramento Peak reported strong Ca XV
emission on the southeast limb today near S18.  Extremely intense emission
was observed yesterday near this same location and may have been related to
Region 7125.

     No new regions were assigned.

     Solar activity should continue low from the visible regions.  A few
minor C-class subflares can be expected from Regions 7123 and 7125.  There is
also a chance for a limb-related M-class event if the source responsible for
todays uncorrelated C9 event is near the east limb.  The only region due to
return over the next 72 hours is old Region 7112 which was near N01 when it
departed the west limb two weeks ago.  This region was small and
insignificant when it departed the west limb and very well may not have
survived on the far side of the sun.

     The geomagnetic field continued to exhibit unstable tendencies.  It
began the day at quiet to unsettled levels and rapidly intensified to minor
and major storm levels between approximately 04:30 UT and 09:00 UT.  This
activity was not long-lived, however, and returned to generally unsettled
levels by the end of the UT day.  A source for this activity is not clear.
There were two coronal mass ejections that occurred on 04 April.  One of
these events may have contributed to this activity, although it is somewhat
unlikely since they were both eruptive limb events.

     Between 05:00 UT and 06:30 UT, the auroral oval expanded significantly
to near 57 degrees geomagnetic latitude.  Although auroral luminosity was not
particularly high, high levels of activity including curtains, rays, and
pulsating sheets were observed during this period.  Thereafter, moderately
rapid contraction of the oval was observed as activity began to subside.
This activity appears to have been rather localized in nature, but was
related to a global enhancement in geomagnetic activity.  Auroral activity is
expected to remain sporadically unstable over the next 24 hours.  The auroral
activity watch for middle latitudes will expire at 18Z on 07 April unless
conditions warrant another extension.

     HF propagation conditions were normal over the equatorial and low
latitude regions.  Middle and high latitudes experienced slightly degraded
conditions with notable increases in signal fading and flutter during the
local night sectors.  Although critical F2 frequencies do not appear to have
been very strongly affected by the burst of auroral and geomagnetic activity
over the middle and high latitude regions, moderate to strong signal
instabilities persisted throughout most of the local night and early morning.
Conditions improved substantially over the middle and high latitude regions
as the day progressed and are now near-normal over all regions.  Near-normal
propagation conditions are expected over the next 24 to 72 hours.  A few
additional substorm periods over the high latitudes could produce localized
instabilities for high and polar latitude signal paths, although no
significant degradations are expected.


**  End of Daily Update  **
Newsgroups: sci.space.news