(meteorobs) Meteor Activity Outlook for October 20-26, 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 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.

Northern Taurid (NTA) 02:40 (040) +18
Northern Hemisphere - 1   Southern Hemisphere - 1

Southern Taurid (STA)  02:44 (041) +12
Northern Hemisphere - 2   Southern Hemisphere - 2

Orionids (ORI)  06:24 (96) +16
Northern Hemisphere - 15   Southern Hemisphere - 15

Epsilon Geminids (EGE) 07:04 (106) +27
Northern Hemisphere - 1   Southern Hemisphere - >1

Leo Minorids (LMI)  10:40 (160) +38
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