(meteorobs) Meteor Activity Outlook for November 5-11, 2011

[Robert Lunsford]

During this period the moon reaches its full phase on Thursday November 10th. At this time the moon will lie opposite of the sun and will be present in the sky all night long. This will be the worse time to try and view meteor activity this month as the brilliant moonlight will obscure all but the brightest meteors. This weekend the waxing gibbous moon will set during the early morning hours and will allow a short glimpse of early November meteor activity under dark conditions. The estimated total hourly rates for evening observers this week is near three as seen from the northern hemisphere and two as seen from the southern hemisphere. For morning observers the estimated total hourly rates should be near fifteen as seen from mid-northern latitudes and ten from mid-southern latitudes. 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 this week 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 5/6. 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:

Remnants from the famous Andromedid (AND) shower, noted for intense storms during the 19th century, may still be seen throughout November. The current position of this large radiant is 01:26 (022) +27. This position lies in a sparse area of northeastern Pisces. The nearest bright star is third magnitude Alpha Trianguli, which lies five degrees to the northeast. The radiant is so diffuse that Andromedid meteors may be seen coming from southern Andromeda, Triangulum, and northwestern Aries as well as eastern Pisces. Visual activity is expected to be low, but detectable. An inconspicuous maximum occurs on November 12. The Andromedid meteors are best seen near 2200 (10pm) LST (Local Standard Time), when the radiant lies on the meridian. At 19km/sec., the average Andromedid will appear as a very slow moving meteor.

The Northern Taurids (NTA) are active from a large radiant centered at 03:35 (054) +22. This position lies in western Taurus, three degrees southwest of the famous naked eye cluster known as the Pleiades (seven sisters). The radiant is best placed near 0100 LST, when it lies highest above the horizon. Since the radiant is large, Northern Taurid meteors may also appear to come from Aries, southern Perseus, as well as western Taurus. Meteors from the Northern Taurids strike the atmosphere at 29km/sec., which would produce meteors of slow velocity. Expected rates would be near two per hour, no matter your location.

The center of the Southern Taurid (STA) radiant now lies 03:39 (055) +14. This position also lies in western Taurus, but ten degrees south of the Pleiades.  The radiant is also best placed near the meridian at 0100 LST, but activity may be seen all night long. Since the radiant is large, Southern Taurid meteors may also appear to come from Aries as well as Taurus. 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.

The Orionids (ORI) remain weakly active from a radiant located at 07:11 (108) +16. This position lies in southern Gemini, five degrees east of the second magnitude star Alhena (Gamma Geminorum). The radiant is best placed near 0400 LST, when it lies highest above the horizon. At 67km/sec., the average Orionid is swift with the brightest meteors producing persistent trains.

The Leonids (LEO) are just now coming to life from a radiant located at 09:48 (147) +25. This position lies in western Leo only one degree north of the third magnitude star Algenubi (Epsilon Leonis). Maximum activity is still more than a week away so current rates would most likely be less than one per hour. At 71km/sec., the average Leonid is swift with a high percentage of trains. 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.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately eleven 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 five 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 but may be used for the entire period.

Andromedids (AND) - 01:26 (022) +27   Velocity - 19km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Northern Taurids (NTA) - 03:35 (054) +22   Velocity - 29km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr.

Southern Taurids (STA) - 03:39 (055) +14   Velocity - 29km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - 1 per hr.

Orionids (ORI) - 07:11 (108) +16   Velocity - 67km/sec.
Northern Hemisphere -1 per hr. Southern Hemisphere - 1 per hr.

Leonids (LEO) - 09:48 (147) +25   Velocity - 71km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Clear Skies!
Robert Lunsford
American Meteor Society