Meteor Activity Outlook for October 20-26, 2006

Meteor rates continue to be strong as seen from the northern hemisphere. The antihelion radiant has now merged with the two Taurid radiants producing slow meteors during the late evening and early morning hours. Meteors from the Orionid radiant are visible most of the month. Strong sporadic rates continue during the morning hours as long as the moon is below the horizon. From the southern hemisphere, sporadic rates have reached their nadir and begin a slow recovery the second half of the month. Meteors from the Taurid and Orionid radiants also help to fill the southern skies with more activity than has been seen since July. A new moon during the peak of the Orionid shower is a plus for all and should help inflate meteor totals that have suffered since the Perseid maximum back in August.

This week the moon reaches its new phase on Sunday October 22. At this time the moon will rise and set with the sun and will not be a factor in observing. Next week the waxing crescent moon will enter the evening sky but will set soon after the end of evening twilight. The estimated total hourly rates for evening observers this week is near four for those north of the equator and two for observers south of the equator. For morning observers the estimated total hourly rates should be near thirty five for northern observers and twenty five for those south of the equator. These rates assume that you are watching from rural areas away from all sources of light pollution. 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 listed below are exact for Saturday night/Sunday morning October 21/22. 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. 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.

These showers are expected to be active this week:

At this time of year debris from comet 2P/Encke produces a double radiant very close to the position of the antihelion radiant. From now through the end of November, it is impossible to resolve the antihelion meteors from those produced by comet 2P/Encke. Therefore we suggest that observers simply classify meteors from this area as either north or south Taurids. Although the radiants actually lie in Aries during October, they reach maximum activity in November when they are situated in the constellation of Taurus.

The Northern Taurid (NTA) radiant is now centered at 02:40 (040) +18. This position lies in central Aries, seven degrees southeast of the second magnitude star Hamal (Alpha Arietis). The Southern Taurid (STA) radiant lies at 02:44 (041) +12. This position lies in southeastern Aries, one degree north of the faint star Mu Ceti. The two radiants are separated by slightly over five degrees. Since they have nearly the same right ascension (celestial longitude), it is difficult to distinguish meteors that move north or south out of the radiants. It is slightly less difficult to distinguish those meteors traveling east or west.

These radiants are above the horizon most of the night and are best placed near 0100 LDT, when they lie on the meridian and are located highest in the sky. Rates at this time should be near two per hour for the southern radiant and one per hour for the northern radiant, regardless of your location. With an entry velocity near 30 km/sec., the average Taurid meteor would be of medium-slow speed.

The Orionids (ORI) are active from a radiant located at 06:24 (96) +16. This position lies in northeastern Orion, three degrees west of the second magnitude star Alhena (Gamma Geminorum). The radiant rises near 2300 LDT and is best placed on the meridian near 0500. With maximum activity predicted for October 21, current rates for all locations would be near fifteen per hour over the weekend, decreasing to near ten per hour late in the period. At 64km/sec., the average Orionid is swift.

The Epsilon Geminids (EGE) peaked on October 18 with a predicted ZHR of two. Current rates would most likely be near one shower member per hour for those observing from the northern hemisphere. Further south, rates would most likely be less than one per hour. This radiant is currently located at 07:04 (106) +27, which places it in central Gemini, four degrees northeast of the third magnitude star Epsilon Geminorum. The radiant is best placed near 0500 when it lies highest in the sky. To differentiate this shower from the nearby Orionids, one must have both radiants within their field of view. Meteors traveling north or south out of the radiants should be easy to classify. Those moving east or west will be more difficult as you must rely on path length and angular velocity to make a correct classification. At 70km/sec., the average Epsilon Geminid is swift with a high percentage of persistent trains.

The Leo Minorids (LMI) are active for only one week centered on October 24. ZHR's are usually low but the radiant is far removed from the Orionids and Epsilon Geminids so that any possible shower members should be easily identified. This radiant is currently located at 10:40 (160) +38, which places it in northeastern Leo Minor, two degrees east of the fourth magnitude star Beta Leo Minoris The radiant is best placed just before dawn when it lies highest in a dark sky. This shower is better situated for observers situated in the northern hemisphere where the radiant rises far higher into the sky before the start of morning twilight. At 62km/sec., the average Leo Minorid is swift.

Sporadic rates have reached the late year plateau for observers located in the northern hemisphere. One would expect to see perhaps sixteen random meteors during the last hour before dawn from rural observing sites. During the first dark hour after the end of evening twilight, perhaps four random meteors can be seen per hour. Sporadic rates increase as the night progresses so rates seen near midnight would be near ten per hour. Sporadic rates seen from the southern hemisphere have passed their annual minimum and are rising again. One would expect to see approximately five random meteors per hour during the last hour before dawn and two per hour during the first dark hour after the end of evening twilight. Rates near midnight would be near four per hour.

Clear Skies!