(meteorobs) Meteor Activity Outlook for November 13-19, 2010

lunro.imo.usa at cox.net lunro.imo.usa at cox.net
Sat Nov 13 14:53:42 EST 2010


As seen from the northern hemisphere, meteor rates continue to be strong in November. While no major activity is expected this month, the two Taurid radiants plus the Leonids keep the skies active. The addition of strong sporadic rates make November one of the better months to view meteor activity from north of the equator. Skies are fairly quiet as seen from the southern hemisphere this month. Activity from the three showers mentioned above may be seen from south of the equator, but the sporadic rates are much lower than those seen in the northern hemisphere. 

During this period the moon reaches its first quarter phase on Saturday November 13th. At this time the moon lies ninety degrees east of the sun and sets near midnight LST (Local Standard Time). Thus evening observers will have moonlight to contend with this weekend. Sucessful observations can still be undertaken as long as the moon is kept out of your field of view. The light of the fist quarter moon is much less intense than that of a full moon and many meteors can still be seen, especially under transparent skies. As the week progresses the waning gibbous moon become more of a problem as it grows brighter and sets later and later during the early morning hours. The estimated total hourly rates for evening observers this week is near three from the northern hemisphere and two for observers south of the equator. For morning observers the estimated total hourly rates should be near twenty five from the northern hemisphere and fourteen as seen from the southern hemisphere. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Evening rates are reduced due to moonlight. 

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning November 13/14. These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies at the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night. 

The following showers are expected to be active this week: 

Sirko Molau and Juergen Rendtel's studies of video radiants has revealed that activity from the famous Andromedid shower, noted for intense storms during the 19th century, may still be seen throughout November. The current position of the large radiant is 01:33 (023) +33. This position lies in western Triangulum, between the stars Mirach (Beta Andromedae) and Alpha Triangulum. Visual activity is expected to be low, but detectable. An inconspicuous maximum occurred on November 12. The Andromedid meteors are best seen near 2200 (10pm) LST when the radiant lies on the meridian. At 19km/sec., the average Andromedid will appear as a very slow moving meteor. Sirko mentions that these meteors are "conspicuously slow and of almost constant activity" during this month. 

Another shower verified by video means are the Omicron Eridanids (OER). This shower is active from November 13-20 with maximum activity occurring on the 14th. If you want any chance of seeing any activity from this shower you had better try this weekend. The waxing gibbous moon will greatly compromise conditions as the week progresses. The radiant is currently located at 04:02 (060) -01. This position lies in eastern Eridanus, fifteen degrees northwest of zero magnitude Rigel (Beta Orionis) and seven degrees south of fourth magnitude star Nu Tauri. The radiant is best placed near 0100 LST, when it lies highest above the horizon. Current rates would most likely be less than one per hour. At 27km/sec., the average Omicron Eridanid is slow. 

The center of the large Northern Taurid (NTA) radiant lies at 04:02 (061) +23. This area of the sky is located in central Taurus, four degrees southeast of the famous naked eye open cluster known as the Pleiades. These meteors are best seen near 0100 LST, when the radiant lies highest above the horizon. This shower peaks on November 13, so rates should be near three per hour all week long. Meteors from the Northern Taurids strike the atmosphere at 29km/sec., which would produce meteors of slow velocity. This shower is also responsible for many of the fireball reports seen in November. 

The center of the large Southern Taurid (STA) radiant lies at 04:06 (062) +15. This area of the sky is located in central Taurus, seven degrees southwest of the first magnitude orange star Aldebaran (Alpha Tauri). The meteors are also best seen near the meridian near 0100 LST. This shower will end this week so rates will only be near one per hour no matter your location. Striking the atmosphere at 29 km/sec., the average Southern Taurid meteor travels slowly through the skies. 

The November Orionids (NOO) were recently discovered by analyzing video data. For years it was lost in the maze of radiants active this time of year. Due to the low activity, visual observers were unable to detect this shower. This shower is active from November 18 through December 9. Maximum activity occurs on November 30. Once you know the radiant in advance, this shower is actually quite oticable, producing an average of two shower members per hour near maximum. Current rates would most likely be less than one per hour, no matter your location. The radiant is currently located at 05:18 (079) +13. This position lies in northen Orion, six degrees north of the second magnitude star Bellatrix (Gamma Orionis). These meteors are best seen near 0200 LST when the radiant lies on the meridian and highest above the horizon. At 44 km/sec. the November Orionids produce mostly medium velocity meteors. 

The Alpha Monocerotids (AMO) are active from November 15-25, with maximum occurring on the 21st. This shower has produced outbursts in the past but none are expected for many years to come. Rates are expected to be less than one shower member per hour, even on the night of maximum activity. The radiant is currently located at 07:26 (111) +02. This position lies in central Canis Minor, only three degrees southwest of the zero magnitude star Procyon (Alpha Canis Minoris). These meteors are also best seen near 0500 LST when the radiant lies highest above the horizon in a dark sky. At 65 km/sec. the Alpha Monocerotids produce mostly swift meteors. 

The Leonids (LEO) are expected to peak on the Thursday morning November 18. Unfortunately this is just three days before the full moon so moonlight will be a major factor in reducing the activity you see. A few Leonids may be seen this weekend during the late morning hours from a radiant located at 10:07 (152) +23. This position lies in western Leo (within the "sickle") only two degrees southwest of the third magnitude star Adhafera (Zeta Leonis). The area of the sky does not clear the eastern hornizon until the late evening hours so no Leonid activity can be seen during the early evening hours. These meteors are best seen during the last hour before the onset of morning twilight, when the radiant lies highest above the horizon in a dark sky. Rates would most likely be 2-3 per hour all week long. At 71km/sec., the average Leonid is swift with a high percentage of trains. 

As seen from the mid-northern hemisphere (45N) one would expect to see approximately sixteen sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near two per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near six per hour as seen from rural observing sites and one per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Evening rates are reduced due to moonlight. 

The list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning. 

Andromedids (AND) - 01:33 (023) +33   Velocity - 19km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Omicron Eridanids (OER) - 04:02 (060) -01  Velocity - 27km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Northern Taurids (NTA) - 04:02 (061) +23   Velocity - 29km/sec.
Northern Hemisphere - 3 per hr. Southern Hemisphere - 3 per hr.

Southern Taurids (STA) - 04:06 (062) +15  Velocity - 29km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - 1 per hr.

November Orionids (NOO) - 05:18 (079) +13  Velocity - 44km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Alpha Monocerotids (AMO) - 07:26 (111) +02  Velocity - 65km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Leonids (LEO) - 10:07 (152) +23  Velocity - 71km/sec.
Northern Hemisphere - 3 per hr. Southern Hemisphere - 2 per hr
              
*For a detailed explanation on the different classes of meteor showers and other astronomical terms, please visit: http://www.amsmeteors.org/showers.html#X2010 

Clear Skies!
Robert Lunsford 
American Meteor Society



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