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- To: sun-earth@SkyandTelescope.com
- Subject: AstroAlert: General HIGH Solar Activity Alert & Aurora Watch
- From: Cary Oler <oler@solar.spacew.com>
- Date: Fri, 19 Jul 2002 03:42:41 -0600 (MDT)
- Delivered-To: gramy@globedot net.nz
- Sender: owner-sun-earth@SkyandTelescope.com
================================================================= This Is SKY & TELESCOPE's AstroAlert for Sun-Earth Interactions ================================================================= A s t r o A l e r t Sun-Earth Alert Solar Terrestrial Dispatch http://www.spacew.com 19 July 2002 Watch solar activity in real-time: http://www.spacew.com/sunnow (updated every minute) Additonal imagery and information: http://www.spacew.com/astroalert.html GENERAL HIGH SOLAR ACTIVITY ALERT & AURORA WATCH Some exciting and powerful activity is occurring on the Sun. We encourage all solar observers to help in observing the activity. Sunspot complex Region 10030 has produced several major solar flares over the past few days. The latest was a class X1.8 solar x-ray flare at 07:44 UTC on 18 July. This event was associated with a fast coronal mass ejection that had an Earthward directed component (expected to impact the Earth soon). This is discussed in greater detail below. In approximately 4 days, this spot complex will rotate behind the western limb of the Sun and will be lost from view. It is in a state of gradual decay, but is still quite capable of producing energetic solar flare activity. It was a naked-eye sunspot complex as it rotated through the central solar meridian. The other major sunspot complex being monitored is Region 10036. It is located on the eastern side of the Sun and is already identified (by John C. McConnell on 18 July) as a naked-eye sunspot complex. It has not yet produced any significant energetic solar flare activity, but certainly has the potential to do so at any time. This spot complex will remain a good target for protected naked eyes and telescopic observations for some time. It is expected to transit through the central meridian in about 3 days and will remain on the visible side of our Sun for almost another 10 days. It may produce some influential levels of solar activity by then. Another area of significant interest is an as-yet unseen sunspot complex that is beginning to approach the eastern solar limb. Over the last week or so, this unseen sunspot complex has been responsible for producing some very powerful coronal mass ejections on the back side of the Sun. These coronal mass ejections have been imaged by the Solar and Heliospheric Observatory (SOHO). Some of the mass ejections have been clocked travelling at velocities up to around 1,600 kilometers per second. In layman's language, this is 5.76 million kilometers per hour or 3.6 million miles per hour). Velocities this high are difficult to imagine, so to help place this into perspective, imagine that a skilled astronaut could pilot a space vehicle at 1,600 km/sec. At this velocity, s/he could reach the Sun's surface in a little over one day's time. A trip to the Moon would only take about 4 minutes. The sunspot complex responsible for these powerful and fast coronal mass ejections is expected to begin rotating into view around the eastern limb of the Sun over the weekend or very early next week. When it does, assuming the spot complex remains as volatile as it has been on the backside of the Sun, we may begin to see additional major solar flare activity. Amateur solar observers are encouraged to keep a close eye on the eastern limb of the Sun for possible signs of limb-based energetic activity. Those who have H-alpha filters that can be safely viewed through telescopes may witness some exciting activity. Energetic limb activity can produce spectacular surges where mass seems to stream out into space in a beautiful thread-like appearance. Impressive limb sprays where mass from the Sun appears to be suddenly "sprayed" into space are also common with energetic limb activity. Rarer forms of solar prominences can also be observed - for example, loop prominences are often visible in H-alpha following strong solar flares on the limb. These beautiful loops of material can appear very bright against the blackness of space and typically form during and after strong solar flare events (also known as post-flare loops). We encourage amateurs to report any observed and interesting activity to: STD@Spacew.Com. Observations of strong solar flares in H-alpha are also encouraged (please make certain you include the UTC time of your observations and be descriptive with what you see). Observers who are limited to observing the Sun in white-light are encouraged to watch for glimpses of possible white-light flares should solar activity become intense enough to produce such rare events. White light observers should also watch for rapid changes in sunspot structure. Rapid growth and decay often accompany significant solar activity. The appearance of a sunspot complex can change rapidly in just a matter of hours. If you don't own a telescope, or a filter capable of observing the Sun, you can obtain current real-time images of the Sun in h-alpha at: http://www.spacew.com/sunnow. We are collaborating with numerous professional solar observatories worldwide to provide real-time h-alpha images to the amateur and professional scientific community. Imagery is updated up to once every minute. Daily archive records of h-alpha activity are also available in movie format at this site. When all observatories are cloudless, we are able to supply about 21 hours a day of continuous coverage. Big Bear Solar Observatory is also providing excellent real-time h-alpha imagery at: http://www.bbso.njitdot edu/Research/Halpha/ha_1minbw.html (but only between roughly 15:00 and 01:00 UTC daily [11 am and 9 pm EDT]). TWO MERGING EARTHWARD-DIRECTED CORONAL MASS EJECTIONS On 17 and 18 July, two major solar flares from Region 10030 produced a pair of coronal mass ejections that have the potential of producing periods of active to moderately strong auroral activity on 19 and 20 July. If the two disturbances constructively merge, periods of auroral storm activity may be observed that might produce sporadic episodes of visible activity throughout many dark-sky middle latitude regions. Otherwise, most of the activity may end up remaining confined to the higher latitudes. In response to these events, the Middle Latitude Auroral Activity Watch is being extended. If predictions hold true, activity could begin increasing with the arrival of the disturbances late in the UTC day of 19 July or early on 20 July. For North American observers, this corresponds to the late afternoon and evening hours of Friday, 19 July. Observers who spot activity are encouraged to report their findings to the Global Auroral Activity Network at http://www.spacew.com/submitsighting.html. Anyone interested in monitoring the vast resources of images on the Internet and staying informed on current solar activity and auroral activity are encouraged to download the free trial version of SWIM (www.spacew.com/swim). A copy of the Middle Latitude Auroral Activity Watch is included below. /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ MIDDLE LATITUDE AURORAL ACTIVITY WATCH WATCH EXTENDED: 08:00 UTC, 19 JULY 2002 /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ VALID BEGINNING AT: IN-PROGRESS, BUT OF MOST CONCERN AFTER: 15:00 UTC 19 JULY VALID UNTIL: 19:00 UTC (3 pm EDT) ON 21 JULY HIGH RISK PERIOD: 19 - 20 JULY (UTC DAYS) MODERATE RISK PERIOD: 19 - 21 JULY PREDICTED ACTIVITY INDICES: 15, 35, 15, 15 (19 JULY - 22 JULY) POTENTIAL MAGNITUDE OF MIDDLE LATITUDE AURORAL ACTIVITY: MODERATE POTENTIAL DURATION OF THIS ACTIVITY: MAIN BELT = 12 HOURS MINOR BELT = 12 TO 24 HOURS ESTIMATED OPTIMUM OBSERVING CONDITIONS: NEAR LOCAL MIDNIGHT EXPECTED LUNAR INTERFERENCE: MODERATE OVERALL OPPORTUNITY FOR OBSERVATIONS FROM MIDDLE LATITUDES: FAIR AURORAL ACTIVITY *MAY* BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM... OREGON TO SOUTHERN IDAHO TO WYOMING TO NORTHERN NEBRASKA TO IOWA TO ILLINOIS TO INDIANA TO OHIO TO PENNSYLVANIA TO NEW JERSEY. ACTIVITY *MAY* ALSO BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM... IRELAND TO SOUTHERN ENGLAND TO NORTHERN BELGIUM TO CENTRAL GERMANY TO NORTH-CENTRAL POLAND TO NORTHERN BELARUS TO NORTHERN RUSSIA (ROUGHLY NORTH OF A LINE FROM TVER TO YAROSLAVL TO SYKTYVKAR TO CENTRAL SIBERA). NEW ZEALAND AND EXTREME SOUTHERN REGIONS OF AUSTRALIA MAY ALSO SPOT PERIODS OF ACTIVITY. SYNOPSIS... A pair of Earthward-directed coronal mass ejections (CMEs) from recent major solar flares in active sunspot complex 10030 are expected to reach the Earth late on 19 July or early on 20 July (UTC time). This translates to the late afternoon and evening hours of 19 July for North American observers. Dark-sky observers should be alert for possible periods of moderately strong auroral activity on these days. Significant auroral storming is not presently anticipated although complex structures in the solar wind may accompany this disturbance as the faster of the two CMEs is expected to merge with the slower of the two near the Earth. As a result, there is a chance some periods of activity may be briefly unexpectedly strong if constructive interaction occurs between the two CMEs. The active sunspot complex that was associated with these two earthward directed CMEs may still produce additional earthward directed CMEs over the coming days. However, it is in a state of gradual decay and the frequency of significant activity from this spot complex may similarly decrease. A second sunspot complex of developing concern is rotating into a better position for producing potentially influential earthward-directed CMEs. Region 10036 has not yet produced any major solar flare activity, but is growing and increasing in magnetic complexity. It is currently capable of producing a major flare. This spot complex will remain a possible threat through at least the next week. Behind this spot complex is a third spot complex that has not yet rotated into view around the eastern limb of the Sun. It is believed to be responsible for producing numerous very strong coronal mass ejections on the backside of the Sun. If this spot complex retains its integrity and structure through the next week or two, it may also pose as a future threat. This watch will remain valid through 19:00 UTC (3 pm EDT) on 21 July. It will then be updated or allowed to expire. For updated information, visit: http://www.spacew.com/aurora/forum.html PLEASE REPORT OBSERVATIONS OF AURORAL ACTIVITY TO: http://solar.spacew.com/submitsighting.html Observations reported here are permanently recorded for future study and are immediately made available in real-time to a large network of observers world-wide via the Internet, e-mail and pager. If you observe activity, your assistance to contribute to this database would be appreciated. A FREE trial of the space weather "SWIM" software package is now available at: http://www.spacew.com/swim. Use it to monitor current conditions. It may also be used to monitor any image resource you find on the Internet (including almost any type of 'cam' or "pictures of the day" you can find). ** End of the AstroAlert Bulletin ** ================================================================== AstroAlert is a free service of SKY & TELESCOPE, the Essential Magazine of Astronomy (http://SkyandTelescope.com/). This e-mail was sent to AstroAlert subscribers. 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