Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from hogtown.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Fri, 24 May 91 02:51:56 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 24 May 91 02:51:50 -0400 (EDT) Subject: SPACE Digest V13 #575 SPACE Digest Volume 13 : Issue 575 Today's Topics: SOLAR TERRESTRIAL FORECAST AND REVIEW Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: Thu, 16 May 91 19:36:54 MDT From: oler <@BITNET.CC.CMU.EDU:oler@HG.ULeth.CA> (CARY OLER) Subject: SOLAR TERRESTRIAL FORECAST AND REVIEW X-St-Vmsmail-To: st%"space+@andrew.cmu.edu" --- SOLAR TERRESTRIAL FORECAST AND REVIEW --- May 17 to May 26, 1991 Report Released by Solar Terrestrial Dispatch P.O. Box 357, Stirling, Alberta, Canada T0K 2E0 --------- SOLAR TERRESTRIAL REVIEW FOR 10 MAY TO 16 MAY Solar activity over the past week ranged from low to high. Two major flares highlight the activity. The first major flare erupted from departed Region 6615, which was about a day beyond the west limb when the event was observed. The flare attained a class M8.2 x-ray rating, but was not optically correlated due to the position of Region 6615 beyond the west limb. The flare was accompanied by weak intensity Type II and IV sweeps. The intensity of the sweeps was believed to be diminished due to the poor location of Region 6615 during the event. A flare loop complex was observed over the west limb during this event. The flare also ejected protons at greater than 10 MeV. The protons arrived at the Earth near 03:00 UT on 13 May, less than 2 hours after the flare peak. The proton event caused polar cap ionospheric anomalies which degraded the accuracy of navigational beacon signals over these areas. However, polar cap absorption did not surpass event thresholds for this event. All effects of the proton activity ended on 15 May. The second major solar flare occurred near the time this report was being compiled. The event occurred from Region 6619 and was rated a class M8.9/2B Tenflare. Strong Type II and IV sweeps accompanied this event, which peaked at 07:03 UT on 16 May and lasted for 55 minutes. A satellite proton event was expected to begin near 12:00 UT, but has not yet arrived (and probably will not arrive). A low to moderate impact is possible from this last event. Increased geomagnetic activity is possible on 18 and 19 April. The intensity of the activity is not expected to be particularly high, although periods of minor storming may materialize possible over the northerly middle and particularly the high latitudes on these dates. Periods of minor geomagnetic storming were observed on 13 and 14 May. The cause has not been determined due to a number of events which could have produced the activity. Generally unsettled conditions have been observed since then. Auroral activity was enhanced on 13 and 14 May in conjunction with the geomagnetic activity. Generally moderate levels of auroral activity were observed on these dates over the middle latitudes, while high latitudes experienced periods of high auroral activity. Southerly middle and low latitudes were unable to witness this activity. HF propagation conditions were generally fair to good throughout the week. Some periods of increased signal absorption were observed during M-class flare activity. Increase auroral flutter on the HF bands were noted on 13 and 14 May. More stable conditions were observed thereafter. Polar latitudes experienced degraded HF propagation conditions due to the solar proton event which occurred on 13 and 14 May. Absorption levels did not produce blackout conditions, but did hamper attempts at DX. VHF propagation conditions were generally normal this week. There were several periods where enhanced VHF propagation conditions possibly capable of supporting DX occurred. A sudden enhancement accompanied the satellite proton event, and several M-class long-duration flares were also believed capable of producing enhanced VHF propagation conditions. Some limited auroral backscatter communications were also possible on 13 and 14 May over the northerly middle and high latitude regions. Conditions have since returned to normal. SHORT TERM SOLAR TERRESTRIAL FORECAST Solar activity is expected to remain generally low to moderate over the next week. There is a continuing slight risk for another isolated major flare from Region 6619 before it departs from the western solar hemisphere by about 19 May. The other regions currently visible do not appear to be capable of producing major flares and will probably restrict flaring to the lower M-class levels. We are again experiencing declining solar indices as we head toward a rotational minimum, which should be observed later next week. The rotational minimum 10.7 cm radio solar flux is expected to drop to between 125 and 135 later next week. Geophysical activity will be interesting to observe over the next two weeks. By 18 or 19 May, the effects from the last major flare are expected to begin impinging on the Earth. The location of this last flare was not in a particularly sensitive location, so any impacts we do receive (if we receive any) will probably be low to moderate. There is a slight risk for minor geomagnetic storming to materialize on 19 May, although the risk is not particularly high. But it should be noted as a possibility. If an impact is witnessed, high latitudes will experience the worst conditions, with periods of minor to possibly major storming on 19 and possibly 20 May. By 22-23 May, a recurrent coronal hole is expected to place itself in a position capable of inducing very active to minor storm level geomagnetic conditions. The intensity of the geomagnetic activity could surpass minor storm thresholds over the middle latitudes and may in fact reach low-intensity major storm levels over the high latitudes. The activity is not expected to be as great as was observed in late April, but could still produce frequent periods of minor storming over all latitudes. Magnetic K-indices between 4 and 6 will be possible over the middle latitudes, while high latitudes could witness activity ranging from 5 to 7 on the K-index. A-indices could surpass 25 to 35 over the middle latitudes, particularly between 25 and 27 May when activity is expected to peak. High latitudes could experience A-indices above 40, approaching major storm thresholds on these dates. A more accurate determination of activity will be possible by 20 or 21 May. A potential geomagnetic storm warning may be issued near then if conditions are expected to surpass storm thresholds. Conditions should return to more quiet levels by 31 May or 01 June. Auroral activity is expected to become enhanced late on 18 May and into 19 May in response to the last major solar flare. The intensity of this activity is estimated to become generally moderate over the middle latitudes, with possible periods of high intensity auroral activity over the high latitudes during the late evening hours after the moon sets. This is all dependent on whether an interplanetary shock from the last major class M8.9 flare materializes. There is a possibility that the Earth will escape a terrestrial impact from that flare. However, we are holding to the models which suggest that a low to moderate terrestrial impact will occur late on 18 May or sometime on 19 May. High latitudes could experience fairly impressive levels of auroral activity on 18 and/or 19 May if an impact materializes. Later next week, auroral activity should become (or remain) enhanced as we begin to experience the recurrent effects from the coronal hole which affected us quite dramatically in late April. Fairly constant levels of moderate auroral activity are expected next week, particularly after 22/23 May until 29-31 May. The coming week does not look too impressive for HF radio propagation. Conditions are expected to be below normal throughout most of the remainder of May. Conditions are expected to become somewhat degraded on 18 or 19 May in conjunction with the expected flare impact. The degradation observed at that time is not expected to be too significant, but this is entirely dependent on whether terrestrial activity becomes more disturbed than predicted (the region which spawned the flare was in a "gray" area where the difficulty of forecasting terrestrial impacts with reliable accuracy is higher). Presently, HF radio conditions are expected to become more unstable on 18 or 19 May, with increased fading, noise and distortion. Conditions are not expected to fully recover before coronal impacts begin to affect radio conditions next week. DX will still be possible, but will be less stable. VHF propagation conditions will vary over the next week. Periods of auroral backscatter will be possible on 18 and 19 May over the middle and high latitude regions, provided a flare impact materializes. There is also a chance for isolated periods of sporadic E near the auroral zone and northerly middle latitudes on these dates, again dependent on whether we experience increased geophysical activity from the last major flare. Conditions should then begin to return to normal before coronal impacts begin to increase the probability for auroral backscatter and related activity later next week. A full recovery accompanied by decreased backscatter probabilities is expected by 31 May or 01 June. There are quite a few events which may occur over the coming week. Consult the forecast charts below for information on the possible impacts of these events. SUMMARY OF ALL ACTIVE REGIONS VISIBLE ON THE SOLAR DISK AS OF 16 MAY Region # Location LO Area Class LL Spots Magnetic Type -------- -------- --- ---- ----- -- ----- ------------- 6619 N30W53 266 3090 DKC 10 010 BETA DELTA 6621 N09W53 266 0540 CAO 05 005 BETA 6622 S27W46 259 0150 HAX 02 001 ALPHA 6623 N04W44 257 0030 HAX 01 002 ALPHA 6624 S17W24 237 0660 EKO 12 016 BETA GAMMA 6625 N10W22 235 0600 CSO 08 005 BETA 6630 S11E15 198 0030 BXO 05 006 BETA 6631 N16W25 238 0030 BXO 03 003 BETA 6632 S08W17 230 0030 BXO 05 006 BETA 6633 S12E64 149 0660 DAO 10 005 BETA NOTES: Area is in million square kilometers. Angular extent (LL) and solar longitude (LO) are in degrees. For more information regarding the terminology used above, request the Glossary of Solar Terrestrial Terms from: "oler@hg.uleth.ca". H-ALPHA PLAGES WITHOUT SPOTS. LOCATIONS VALID AS OF 00:00 UT ON 16 MAY REGION LOCATION LO COMMENTS (IF ANY) ------ -------- --- ------------------------------- NO PLAGE REGIONS VISIBLE NONE ACTIVE REGIONS DUE TO RETURN BETWEEN 16 MAY AND 18 MAY Region Latitude Longitude (Helio.) ------ -------- --------- 6606 N08 121 6612 S27 087 NOTES: For definitions regarding the above, request the "Glossary of Solar Terrestrial Terms" from "oler@hg.uleth.ca". GRAPHICAL ANALYSIS OF RECENT PLANETARY (GLOBAL) GEOMAGNETIC ACTIVITY Cumulative Geomagnetic Activity History Peak Planetary Geomagnetic Activity during the past 96 hours ____________________________________________________________________ | EXTREMELY SEVERE | | | | | HIGH | | VERY SEVERE STORM | | | | | HIGH | | SEVERE STORM | | | | | MODERATE | | MAJOR STORM | | | | | LOW - MOD. | | MINOR STORM | * ** | *** | | | LOW | | VERY ACTIVE | **** | ****** | | ***| NONE | | ACTIVE | *******| *******| | *****| NONE | | UNSETTLED |********|********|********|********| NONE | | QUIET |********|********|********|********| NONE | | VERY QUIET |********|********|********|********| NONE | |-------------------|--------|--------|--------|--------|------------| | Geomagnetic Field | Mon. | Tue. | Wed. | Thu. | Anomaly | | Conditions | Given in 3-hourly UT intervals | Intensity | |____________________________________________________________________| NOTES: The data above represents preliminary planetary geomagnetic activity. Data from many magnetic observatories around the world are used in constructing the above chart. The first graph line for each day represents geomagnetic activity which occurred between 00 UT and 03 UT. The second graph line represents activity which occurred between 03 UT and 06 UT, etc. For information regarding the interpretation and/or use of these charts, send a request for the document "Understanding Solar Terrestrial Reports" to: oler@hg.uleth.ca. PEAK PLANETARY 10-DAY GEOMAGNETIC ACTIVITY OUTLOOK (17 MAY - 26 MAY) ________________________________________________________________________ | EXTREMELY SEVERE | | | | | | | | | | | HIGH | | VERY SEVERE STORM | | | | | | | | | | | HIGH | | SEVERE STORM | | | | | | | | | | | MODERATE | | MAJOR STORM | | | | | | | | | | | LOW - MOD. | | MINOR STORM | | *|** | | | | | | * |***| LOW | | VERY ACTIVE | | **|***|***| | | |***|***|***| NONE | | ACTIVE | * |***|***|***|***|***|***|***|***|***| NONE | | UNSETTLED |***|***|***|***|***|***|***|***|***|***| NONE | | QUIET |***|***|***|***|***|***|***|***|***|***| NONE | | VERY QUIET |***|***|***|***|***|***|***|***|***|***| NONE | |-------------------|---|---|---|---|---|---|---|---|---|---|------------| | Geomagnetic Field |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| Anomaly | | Conditions | Given in 8-hour intervals | Intensity | |________________________________________________________________________| OVERALL CONFIDENCE LEVEL: 65% FLARE IMPACT CONFIDENCE LEVEL: 60% FOR 18-20 MAY NOTES: Predicted geomagnetic activity is based heavily on recurrent phenomena. Transient energetic solar events cannot be predicted reliably over periods in excess of several days. Hence, there may be some deviations from the predictions due to the unpredictable transient solar component. GRAPHICAL ANALYSIS OF SOLAR ACTIVITY OVER THE PAST 60 DAYS Cumulative Graphical Analysis of Solar Activity ____________________________________________________________ 275|F | HIGH 264|F *F* F = Major Flare(s) | HIGH 253|FF F * * *F* | HIGH 243|FFFFF * ***F** | Moderate 232|FFFFFF*F F***F*** * | Moderate 221|FFFFFF*FF *F***F****F ***** | Moderate 210|FFFFFF*FF *F***F****F ******F | Moderate 200|FFFFFF*FF* **F***F****F *******F* | Moderate 189|FFFFFF*FF**F*F*F***** **F***F****F *******F** | Low 178|FFFFFF*FF**F*F*F********F***F****F* ********F**F| Low 167|FFFFFF*FF**F*F*F********F***F****F* ********F**F| Low 157|FFFFFF*FF**F*F*F********F***F****F** ***************F**F| Low 146|FFFFFF*FF**F*F*F********F***F****F*** ***************F**F| Low 135|FFFFFF*FF**F*F*F********F***F****F**********************F**F| Low 125|FFFFFF*FF**F*F*F********F***F****F**********************F**F| Very Low ------------------------------------------------------------ Cumulative 60 day Solar Activity Record Start Date: March 18, 1991 NOTES: Left-hand column digits represent the 10.7 cm solar radio flux obtained from Ottawa. The right-hand column describes the relative solar activity for that period based on the average number of major and minor flares that can be expected for related solar flux values. Plot lines labeled with the letter "F" represent days where at least one major flare occurred (ie. class M5 or greater flare). GRAPHICAL 20-DAY SOLAR ACTIVITY PREDICTION Solar Activity _________________________________________________________________ | 227 | | | | | | | | | | | | | | | | | | | | | | 219 | | | | | | | | | | | | | | | | | | | |**| | 211 | | | | | | | | | | | | | | | | | | |**| | | 203 | | | | | | | | | | | | | | | | | | | | | | 195 | | | | | | | | | | | | | | | | | | | | | | 187 | | | | | | | | | | | | | | | | | |**| | | | 179 |**| | | | | | | | | | | | | | | | | | | | | 170 | |**| | | | | | | | | | | | | | |**| | | | | 162 | | |**| | | | | | | | | | | | | | | | | | | 154 | | | |**| | | | | | | | | | | |**| | | | | | 146 | | | | |**| | | | | | | | | |**| | | | | | | 138 | | | | | |**|**| | | | | | |**| | | | | | | | 130 | | | | | | | |**|**|**|**|**|**| | | | | | | | |-----|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--| |Solar|17|18|19|20|21|22|23|24|25|26|27|28|29|30|31|01|02|03|04|05| |Flux | May | June | ----------------------------------------------------------------- CONFIDENCE LEVEL: 70% HF RADIO SIGNAL PROPAGATION PREDICTIONS (17 MAY - 26 MAY) High Latitude Paths ________________________________________________________ | EXTREMELY GOOD | | | | | | | | | | | | VERY GOOD | | | | | | | | | | | CONFIDENCE | GOOD | | | | | | | | | | | LEVEL | FAIR | *| | | | | | | | | | ------- | POOR |** |* | *|* *|***|***|* *|* *| *| | 60% | VERY POOR | | **|** | * | | | * | * |** |***| | EXTREMELY POOR | | | | | | | | | | | |----------------|---|---|---|---|---|---|---|---|---|---| | PROPAGATION |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| | QUALITY | Given in 8-Hour UT Intervals | -------------------------------------------------------- Middle Latitude Paths ________________________________________________________ | EXTREMELY GOOD | | | | | | | | | | | | VERY GOOD | | | | | | | | | | | CONFIDENCE | GOOD |* *|* | | | *|* *| *| | | | LEVEL | FAIR | * | **| *|***|** | * |** |***|* *| *| ------- | POOR | | |** | | | | | | * |** | 65% | VERY POOR | | | | | | | | | | | | EXTREMELY POOR | | | | | | | | | | | |----------------|---|---|---|---|---|---|---|---|---|---| | PROPAGATION |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| | QUALITY | Given in 8-Hour UT Intervals | -------------------------------------------------------- Low Latitude Paths ________________________________________________________ | EXTREMELY GOOD | | | | | | | | | | | | VERY GOOD | | | | | | | | | | | CONFIDENCE | GOOD |***|** | |* *|***|***|* *| *| | | LEVEL | FAIR | | *|***| * | | | * |** |***|* *| ------- | POOR | | | | | | | | | | * | 65% | VERY POOR | | | | | | | | | | | | EXTREMELY POOR | | | | | | | | | | | |----------------|---|---|---|---|---|---|---|---|---|---| | PROPAGATION |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| | QUALITY | Given in 8-Hour UT Intervals | -------------------------------------------------------- NOTES: NORTHERN HEMISPHERE SOUTHERN HEMISPHERE High latitudes >= 55 deg. N. | High latitudes >= 55 deg. S. Middle latitudes >= 40 < 55 deg. N. | Middle latitudes >= 35 < 55 deg. S. Low latitudes < 40 deg. N. | Low latitudes < 35 deg. S. POTENTIAL VHF DX PROPAGATION PREDICTIONS (17 MAY - 26 MAY) INCLUDES SID AND AURORAL BACKSCATTER ENHANCEMENT PREDICTIONS HIGH LATITUDES __________________________________________________ ___________________ | SIGNAL | Given in 8 hour local time intervals | | SID ENHANCEMENT | | QUALITY |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| |F|S|S|M|T|W|T|F|S|S| |__________|___|___|___|___|___|___|___|___|___|___| |-|-|-|-|-|-|-|-|-|-| | VERY GOOD| | | | | | | | | | | 0%|*|*|*|*|*|*|*|*|*|*| |ABOVE NORM| | | | | | | | | | | 20%|*|*|*|*|*|*|*|*|*|*| | NORMAL|***|** | | **|***|***| * | * | | | 40%|*|*|*|*| | | | | | | |BELOW NORM| | *|***|* | | |* *|* *|***|***| 60%| | | | | | | | | | | | VERY POOR| | | | | | | | | | | 80%| | | | | | | | | | | | BLACKOUT| | | | | | | | | | |100%| | | | | | | | | | | |==========|===|===|===|===|===|===|===|===|===|===| |-------------------| | 100% | | | | | | | | | | |100%| | | | | | | | | | | | 80% | | | | | | | | *|* *|* *| 80%| | | | | | | | |*|*| | 60% | | *|* | | | |* *|* *|***|***| 60%| |*|*| | | | |*|*|*| | 40% | | **|***|* *|* *|* *|***|***|***|***| 40%|*|*|*|*| | |*|*|*|*| | 20% |***|***|***|***|***|***|***|***|***|***| 20%|*|*|*|*|*|*|*|*|*|*| | 0% |***|***|***|***|***|***|***|***|***|***| 0%|*|*|*|*|*|*|*|*|*|*| |----------+---|---|---|---|---|---|---|---|---|---| |-|-|-|-|-|-|-|-|-|-| |CHANCE OF |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| |F|S|S|M|T|W|T|F|S|S| | VHF DX | Given in 8 hour local time intervals | |AURORAL BACKSCATTER| |__________|_______________________________________| |___________________| MIDDLE LATITUDES __________________________________________________ ___________________ | SIGNAL | Given in 8 hour local time intervals | | SID ENHANCEMENT | | QUALITY |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| |F|S|S|M|T|W|T|F|S|S| |__________|___|___|___|___|___|___|___|___|___|___| |-|-|-|-|-|-|-|-|-|-| | VERY GOOD| | | | | | | | | | | 0%|*|*|*|*|*|*|*|*|*|*| |ABOVE NORM| | | | | | | | | | | 20%|*|*|*|*|*|*|*|*|*|*| | NORMAL|***|* | * | * |***|***| * | * | | | 40%|*|*|*|*| | | | | | | |BELOW NORM| | **|* *|* *| | |* *|* *|***|***| 60%| | | | | | | | | | | | VERY POOR| | | | | | | | | | | 80%| | | | | | | | | | | | BLACKOUT| | | | | | | | | | |100%| | | | | | | | | | | |==========|===|===|===|===|===|===|===|===|===|===| |-------------------| | 100% | | | | | | | | | | |100%| | | | | | | | | | | | 80% | | | | | | | | | | | 80%| | | | | | | | | | | | 60% | | *|* | | | | | *|* *|* *| 60%| | | | | | | | |*|*| | 40% | | **|***|* *| | |* *|* *|***|***| 40%| |*|*| | | | |*|*|*| | 20% | **|***|***|***|***|***|***|***|***|***| 20%|*|*|*|*|*|*|*|*|*|*| | 0% |***|***|***|***|***|***|***|***|***|***| 0%|*|*|*|*|*|*|*|*|*|*| |----------+---|---|---|---|---|---|---|---|---|---| |-|-|-|-|-|-|-|-|-|-| |CHANCE OF |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| |F|S|S|M|T|W|T|F|S|S| | VHF DX | Given in 8 hour local time intervals | |AURORAL BACKSCATTER| |__________|_______________________________________| |___________________| LOW LATITUDES __________________________________________________ ___________________ | SIGNAL | Given in 8 hour local time intervals | | SID ENHANCEMENT | | QUALITY |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| |F|S|S|M|T|W|T|F|S|S| |__________|___|___|___|___|___|___|___|___|___|___| |-|-|-|-|-|-|-|-|-|-| | VERY GOOD| | | | | | | | | | | 0%|*|*|*|*|*|*|*|*|*|*| |ABOVE NORM| | | | | | | | | | | 20%|*|*|*|*|*|*|*|*|*|*| | NORMAL|***|** | **|***|***|***|***|** | * | * | 40%|*|*|*|*| | | | | | | |BELOW NORM| | *|* | | | | | *|* *|* *| 60%| | | | | | | | | | | | VERY POOR| | | | | | | | | | | 80%| | | | | | | | | | | | BLACKOUT| | | | | | | | | | |100%| | | | | | | | | | | |==========|===|===|===|===|===|===|===|===|===|===| |-------------------| | 100% | | | | | | | | | | |100%| | | | | | | | | | | | 80% | | | | | | | | | | | 80%| | | | | | | | | | | | 60% | | | | | | | | | | | 60%| | | | | | | | | | | | 40% | * | **|***| * | | | | *|* *|* *| 40%| | | | | | | | |*|*| | 20% |***|***|***|***|***|***|***|***|***|***| 20%| |*|*| | | | |*|*|*| | 0% |***|***|***|***|***|***|***|***|***|***| 0%|*|*|*|*|*|*|*|*|*|*| |----------+---|---|---|---|---|---|---|---|---|---| |-|-|-|-|-|-|-|-|-|-| |CHANCE OF |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| |F|S|S|M|T|W|T|F|S|S| | VHF DX | Given in 8 hour local time intervals | |AURORAL BACKSCATTER| |__________|_______________________________________| |___________________| NOTES: These VHF DX prediction charts are defined for the 50 MHz to 220 MHz bands. They are based primarily on phenomena which can affect VHF DX propagation globally. They should be used only as a guide to potential DX conditions on VHF bands. Latitudinal boundaries are the same as those for the HF predictions charts. For more information, request the document "Understanding Solar Terrestrial Reports" from: "oler@hg.uleth.ca". AURORAL ACTIVITY PREDICTIONS (17 MAY - 26 MAY) High Latitude Locations ________________________________________________________ | EXTREMELY HIGH | | | | | | | | | | | CONFIDENCE | VERY HIGH | | | | | | | | | | | LEVEL | HIGH | | * | | | | | | | * |***| ------- | MODERATE | |***|***| * | * | * |***|***|***|***| 60% | LOW |***|***|***|***|***|***|***|***|***|***| | NOT VISIBLE |***|***|***|***|***|***|***|***|***|***| |----------------|---|---|---|---|---|---|---|---|---|---| | AURORAL |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| | INTENSITY | Eve.Twilight/Midnight/Morn.Twilight | -------------------------------------------------------- Middle Latitude Locations ________________________________________________________ | EXTREMELY HIGH | | | | | | | | | | | CONFIDENCE | VERY HIGH | | | | | | | | | | | LEVEL | HIGH | | | | | | | | | | | ------- | MODERATE | | * | * | | | | | * |***|***| 65% | LOW | * |***|***|***| * | * |***|***|***|***| | NOT VISIBLE |***|***|***|***|***|***|***|***|***|***| |----------------|---|---|---|---|---|---|---|---|---|---| | AURORAL |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| | INTENSITY | Eve.Twilight/Midnight/Morn.Twilight | -------------------------------------------------------- Low Latitude Locations ________________________________________________________ | EXTREMELY HIGH | | | | | | | | | | | CONFIDENCE | VERY HIGH | | | | | | | | | | | LEVEL | HIGH | | | | | | | | | | | ------- | MODERATE | | | | | | | | | | | 60% | LOW | | * | * | | | | | | * | * | | NOT VISIBLE |***|***|***|***|***|***|***|***|***|***| |----------------|---|---|---|---|---|---|---|---|---|---| | AURORAL |Fri|Sat|Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun| | INTENSITY | Eve.Twilight/Midnight/Morn.Twilight | -------------------------------------------------------- NOTE: For more information regarding these charts, send a request for the document, "Understanding Solar Terrestrial Reports" to: oler@hg.uleth.ca. ** End of Report ** ------------------------------ End of SPACE Digest V13 #575 *******************