(meteorobs) Meteor Activity Outlook for September 29-October 5, 2006

[Robert Lunsford]

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.

Northern Taurid (NTA) 01:52 (022) +12 29
Northern Hemisphere - 1   Southern Hemisphere - 1

Southern Taurid (STA)  02:04 (025) +07 27
Northern Hemisphere - 2   Southern Hemisphere - 2

Delta Aurigids (DAU)  05:36 (084) +49 64 05:00
Northern Hemisphere - 1   Southern Hemisphere - >1

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2006

Clear Skies!
Robert Lunsford
American Meteor Society