Meteor Activity Outlook for October 18-24, 2008

Meteor activity in general increases in October
when compared to September. A major shower (the Orionids) is active most of the
month along with several minor showers. Both branches of the Taurids become more
active as the month progresses, providing slow, graceful meteors to the nighttime
scene. The Orionids are the big story of the month reaching maximum activity
on the 21st. This display can be seen equally well from both hemispheres
which definitely helps out observers located in the sporadic-poor southern hemisphere
this time of year.

During this period the moon reaches its last
quarter phase on Tuesday October 21st. At this time the moon will rise near 0100
local daylight time and will remain in the sky the remainder of the morning. This
weekend the waning gibbous moon will make meteor watching difficult. Some slow
meteors may be glimpsed during the evening hours before the moon rises, but rates
at this time of night will be low. The estimated total
hourly rates for evening observers this week is near six for those located in
the mid-northern hemisphere (45 N) and three for those viewing from the mid-southern
hemisphere (45 S). For morning observers the estimated total hourly rates should
be near twenty five for those located in the mid-northern hemisphere (45 N) and fifteen
for those viewing from the mid-southern hemisphere (45 S). Locations between these
two extremes would see activity between the listed figures. 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.
Morning rates are reduced due to moonlight.

The radiant positions and rates listed below are exact
for Saturday night/Sunday morning October 18/19. 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:

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 center of the large Northern Taurid (NTA) radiant is now centered at
02:28 (037) +18. This position lies in central Aries, six degrees southeast of
the second magnitude star Hamal (Alpha Arietis). The center of the large Southern
Taurid (STA) radiant lies at 02:36 (039) +12. This position also lies in
southern Aries, twelve degrees southeast of the second magnitude star Hamal (Alpha
Arietis). 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 less
difficult to distinguish those meteors traveling east or west. These radiants are
best placed near the meridian at 0200 LDT. At 29 and 27 km/sec., the average Taurid
meteor travels slowly through the skies.

Sirko Molau’s new studies of video radiants has revealed that the Northern Taurid’s
reach two plateaus of activity with the first occurring on October 20th. The
moon will subdue this activity so it will most likely not be noticed. The same
study has revealed that the Southern Taurids may peak near October 11 and that the
activity for this shower will remain fairly constant through the first week of
November. After that rates will dwindle until these meteors disappear near the
end of November.

The Orionids (ORI) peak on the morning of October 21st from a radiant located
at 06:20 (95) +16. This position lies in extreme eastern Orion, four 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. At 66km/sec., the average Orionid is
swift. A detailed discussion of the Orionids with charts is presented on the AMS
website at: http://www.amsmeteors.org/showers.html#ORI

The Epsilon Geminids (EGE) peak on October 18 radiant with a average ZHR
of only two. Rates near maximum can vary sometimes reaching in excess of five.
The radiant is currently located at 06:56 (104) +27. This position lies in central
Gemini, three degrees northeast of the third magnitude star Epsilon Geminorum.
Current rates will be most likely less than one per hour, especially with the
bright moon in the sky. At 70km/sec., the average Epsilon Geminid is swift.
Sirko Molau’s new studies of video radiants has also revealed that the Epsilon
Geminids may peak as late as October 21st.

Sirko Molau’s studies of video radiants has revealed activity in northern
Cancer between October 10 and November 4, peaking on the October 14th. The radiant
for the Iota Cancrids (ICA) lies at 09:00 (135) +29. This position lies two
degrees east of the fourth magnitude star Iota Cancri. Visual activity is expected
to be low, especially with the bright moon in the morning sky. The radiant rises
near 0200 LDT and is best placed high in the east during the last dark hour of the
morning. At 67km/sec., the average Iota Cancrid will appear move swiftly through
the skies.

Another radiant discovered during Sirko Molau’s studies of video radiants Is the
Tau Ursa Majorids (TUM). This shower is active between October 15th and the 22nd,
peaking on the 16th. The radiant lies at 09:36 (144) +65. This position lies in
western Ursa Major near the faint star 23 Ursae Majoris. Again visual activity is
expected to be low with the bright moon in the morning sky. The radiant is circumpolar
north 25 degrees north latitude and is best seen during the last hour before dawn
when it lies highest above the horizon in a dark sky. At 54km/sec., the average
Tau Ursa Majorid meteor will appear move swiftly through the skies.

The Leo Minorids (LMI) are active from October 17-27 with maximum activity
occurring on October 23rd. 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 10:28 (157) +39, which places it on
the Leo Minor/Ursa major border, just south of a pair of third magnitude stars known
as Mu and Lambda Ursae Majoris. 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.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately
twelve Sporadic meteors per hour during the last hour before dawn as seen from
rural observing sites. Evening rates would be near four per hour. As seen from the
mid-southern hemisphere (45S), morning rates would be near four 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. Morning
rates are reduced during this period due to the bright moon.

The table below presents a summary of the expected activity this week. Rates and
positions are exact for Saturday night/Sunday morning but may be used all week.