(meteorobs) Meteor Activity Outlook for October 12-18, 2007

[Robert Lunsford]

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 in the sporadic-poor southern skies this time of
year.

During this period the moon is a waxing crescent and limited to the evening
sky. Therefore it will not interfere with the prime time morning
observations. The estimated total hourly rates for evening observers this
week is near four for those located in the mid-northern hemisphere (45 N)
and one for observers from the mid-southern hemisphere (45 S). For morning
observers the estimated total hourly rates should be near twenty for those
located in the mid-northern hemisphere (45 N) and eight for those viewing
from the mid-southern hemisphere (45 S). 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 and rates listed below are exact for Saturday
night/Sunday morning October 13/14. 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:

Sirko Molau's studies of video radiants has revealed activity in Ursa Minor
between October 10 and 16, peaking on the 12th. The position at maximum
activity is 16:32 (248) +82. This position lies in central Ursa Minor near
the faint star Epsilon Ursae Minoris. Visual activity is expected to be low,
but detectable. The radiant is best placed as soon as it becomes dark during
the evening hours. At 35km/sec., the average Epsilon Ursae Minorid will
appear as medium-slow.

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 02:12 (033) +16. This
position lies in western Aries, seven degrees south of the second magnitude
star Hamal (Alpha Arietis). The Southern Taurid (STA) radiant lies at 02:20
(035) +11. This position lies in southwestern 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. At 29 and 27
km/sec., the average Taurid meteor travels slowly through the skies.

The Orionids (ORI) are becoming more numerous from a radiant located at
06:04 (91) +15. This position lies in northeastern Orion, eight degrees
north of the orange first magnitude star Betelgeuse (Alpha Orionis). 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 two to three per hour At 66km/sec., the average
Orionid is swift.

The Epsilon Geminids (EGE) are now active from a radiant located at 06:32
(098) +27. This position lies in western Gemini, three degrees northwest of
the third magnitude star Epsilon Geminorum. Maximum activity is predicted to
occur on October 18 with an average ZHR of two. Current rates will be most
likely less than one per hour. Recent studies of video data by Sirko Molau
has indicated that this shower is more active earlier in the month with a
maximum occurring on October 14. Stronger rates occurring now would indicate
the earlier maximum is correct. At 70km/sec., the average Delta Aurigid is
swift.

Sporadic rates have reached maximum for observers in the northern hemisphere
and are now slowly rising for those located south of the equator. One would
expect to see approximately fifteen random meteors during the last hour
before dawn from rural observing sites in the mid-northern hemisphere (45
N). During the first dark hour after the end of evening twilight, perhaps
four random meteors can be seen per hour. As seen from the mid-southern
hemisphere (45 S) late morning rates would now be near four per hour. During
the first dark hour after the end of evening twilight, perhaps one random
meteor can be seen per hour.

Epsilon Ursae Minorids (EUR) 16:32 (248) +82
Northern Hemisphere - <1   Southern Hemisphere - 0

Northern Taurid (NTA) 02:12 (033) +16
Northern Hemisphere - 1   Southern Hemisphere - 1

Southern Taurid (STA)  02:20 (035) +11
Northern Hemisphere - 1   Southern Hemisphere - 1

Orionids (ORI)  06:04 (091) +15
Northern Hemisphere - 2   Southern Hemisphere - 2

Epsilon Geminids (EGE)  06:32 (098) +27
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#2007

Clear Skies!
Robert Lunsford
American Meteor Society