Meteor Activity Outlook for November 14-20, 2009
November 15, 2009
The Meteor Activity Outlook is a weekly summary of expected meteor activity written by Robert Lunsford, Operations Manager of the American Meteor Society and contributor to this blog. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.
As seen from the northern hemisphere, meteor rates continue to be strong in November. While no major showers are active 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 new phase on Monday November 16th. On that date the moon lies close to the sun and is not visible at night. The same circumstances exist for this weekend. As the week progresses the waxing crescent moon will enter the evening sky but still set well before the active morning hours arrive. The estimated total hourly rates for evening observers this week is near five as seen from the northern hemisphere and three from the southern hemisphere. For morning observers the estimated total hourly rates should be near twenty-two from the northern hemisphere and ten 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.
The radiant positions and rates listed below are exact for Saturday night/Sunday morning November 14/15. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.
The following showers are expected to be active this week.
Sirko Molau’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 near the intersection of the constellations of Pisces, Triangulum, and Andromeda. The nearest bright star is second magnitude Mirach (Beta Andromedae), which lies four degrees to the northwest. Visual activity is expected to be low, but detectable. The Andromedid radiant is best placed near 2200 (10pm) local standard time (LST) when it 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 period.
Omicron Eridanids (OER)
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. The radiant is currently located at 04:02 (060) -02. This position lies in eastern Eridanus, fifteen degrees northwest of zero magnitude Rigel (Beta Orionis) and eight 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 be < 1 per hour. At 27km/sec., the average Omicron Eridanid is slow.
Northern Taurids (NTA)
The Northern Taurids (NTA) are active from a large radiant centered at 04:06 (061) +23, which lies in western Taurus, four degrees southeast of the famous naked eye star cluster known as the Pleiades. The radiant is best placed near 0100 LST, when it lies highest above the horizon, but activity may be seen all night long. Meteors from the Northern Taurids strike the atmosphere at 29km/sec., which would produce meteors of slow velocity. Expected rates would be ~3 per hour as seen from the northern hemisphere and ~2 per hour as seen south of the equator.
Southern Taurids (STA)
The center of the large Southern Taurid (STA) radiant lies at 04:09 (062) +15. This position lies in western Taurus, five degrees southwest of the 1st magnitude orange star Aldebaran (Alpha Tauri). The radiant is best placed near the meridian at 0200 LDT, but activity may be seen all night long. Striking the atmosphere at 29 km/sec., the average Southern Taurid meteor travels slowly through the skies. Rates should be near one per hour no matter your location.
November Orionids (NOO)
The November Orionids (NOO) were recently discovered by analyzing video data. This shower is active from November 18 through December 9. Maximum activity occurs on November 30. The radiant is currently (11/18) located at 05:32 (083) +16. This position lies on the Orion/Taurus border, six degrees north of the third magnitude star Lambda Orionis. These meteors are also best seen near 0300 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.
Alpha Monocerotids (AMO)
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 < 1 shower member per hour, even on the night of maximum activity. The radiant is currently located at 07:28 (112) +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) reach maximum activity on the morning of November 17th. The Leonids possess a sharp peak of short duration. These peaks in activity are caused by the Earth passing close to one of the filaments of material produced by comet 55P/Temple-Tuttle. This year the Earth passes close to the several filaments. Between 2100 and 2200 Universal Time (UT) on November 17th, the Earth is expected to pass through three filaments that were produced by 55P/Temple-Tuttle in 1466 and 1533. This timing is best for those watching from central Asia. A fairly strong traditional maximum is also expected near 0900 UT, which is well timed for North America. This corresponds to 0400 EST, 0300 CST, 0200 MST, and 0100 PST on the morning of the 17th. The radiant is currently located at 10:09 (152) +23. This position lies in western Leo, just west of the third magnitude star Zeta Leonis. Rates this weekend are expected to be ~1 per hour. At 70km/sec., the average Leonid is swift with a high percentage of trains. The radiant does not rise until the late evening hours so it is advised to wait until after midnight before beginning serious observations. The radiant is most favorably located during the last dark hour before the onset of morning twilight when it lies highest in a dark sky.
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 four 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 two per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.
The table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning but may be used all week long.
Shower Name RA DEC Vel Rates km/s NH SH AND Andromedids 01h33m +33 19 <1 <1 OER Omicron Eridanids 04h02m -02 27 <1 <1 NTA Northern Taurids 04h06m +23 29 3 2 STA Southern Taurids 04h09m +15 29 1 1 NOO November Orionids 05h32m +16 44 <1 <1 AMO Alpha Monocerotids 07h28m +02 65 <1 <1 LEO Leonids 10h09m +23 70 1 1 RA - Right Ascension DEC - Declination Vel - Velocity relative to Earth (in km per sec) Rates - Rate of visible meteors per hour from a dark site NH - Northern Hemisphere SH - Southern Hemisphere