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 first quarter phase on Saturday September 30. At this time it will set near 0100 local daylight time (LDT) and will not interfere with meteor observing during the prime morning hours. The estimated total hourly rates for evening observers this week is near three for those north of the equator and one for observers south of the equator. For morning observers the estimated total hourly rates should be near twenty for northern observers and eight 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. Evening rates are slightly reduced due to moonlight.
The radiant positions listed below are exact for Saturday night/Sunday morning September 30/October 1. 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 01:52 (022) +12. This position lies in southwestern Aries, seven degrees south of the well-known fourth magnitude double star Mesarthim (Gamma Arietis). The Southern Taurid (STA) radiant lies at 02:04 (025) +07. This position lies in southeastern Pisces, four degrees north of another well-known fourth magnitude double star Al Rischa (Alpha Piscium). 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 0200 LDT, when they lie on the meridian and is 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 Delta Aurigids (DAU) reach peak activity near October 4. Current rates have actually been a bit higher than normal with 1-2 shower members appearing each hour. The radiant is located at 05:36 (84) +49. This position lies in northern Auriga, four degrees northeast of the brilliant zero magnitude star Capella (Alpha Aurigae). As seen from the northern hemisphere, the radiant is above the horizon most of the night and is best placed near 0500 LDT, when it lies on the meridian. Due to the extreme northern declination of this radiant, this shower is only visible from the southern tropics northward. At 64km/sec., the average Delta Aurigid is swift.
A study of the IMO video database by Sirko Molau has shown that there is an active radiant in the constellation of Orion this time of year. This is not the well known Orionid shower, but rather a weak radiant located near Bellatrix (Gamma Orionis). This activity has been recorded from September 24-30 with peak rates near the 27th. The position of this radiant on Sunday morning is expected to be near 05:40 (85) +07 or three degrees east of the second magnitude Bellatrix. This area of the sky is above the horizon most of the night and is best placed near 0500 LDT, when it lies on the meridian. With the radiant lying just north of the celestial equator, this shower would be visible over most of the Earth. Meteors from this radiant strike the Earth with a velocity of 59km/sec. This would produce mostly swift meteors.
Last year near 2000 UT on October 5, a sudden burst of activity was observed from a radiant located at 10:48 (162) +79. This area of the sky is located in extreme western Draco, seventeen degrees north of Dubhe (Alpha Ursae Majoris). This part of the sky is circumpolar as seen from most of the northern hemisphere. Unfortunately this time of year it swings beneath the pole star during the nighttime hours. Far northern observers have the advantage of a higher radiant altitude and longer nights this time of year.
Should this outburst repeat it would most likely occur near 0215 UT on October 6. This timing is favorable for all of Europe and northern Africa. While another repeat performance is unlikely, observers should nevertheless be watching just in case.
Sporadic rates continue to climb slowly for observers located in the northern hemisphere. One would expect to see perhaps fifteen random meteors during the last hour before dawn from rural observing sites. During the first dark hour after the end of evening twilight, perhaps three random meteors can be seen per hour. Sporadic rates increase as the night progresses so rates seen near midnight would be near nine per hour. Sporadic rates seen from the southern hemisphere have reached their annual minimum. One would expect to see approximately four random meteors per hour during the last hour before dawn and one per hour during the first dark hour after the end of evening twilight. Rates near midnight would be near three per hour. Evening rates are slightly reduced due to moonlight.