(meteorobs) Meteor Activity Outlook for October 5-11, 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 reaches its new phase on Thursday October 11. At
this time the moon is located close to the sun and is invisible during the
nighttime hours. This weekend the waning crescent moon is a small nuisance
and less of a problem as the week progresses. The estimated total hourly
rates for evening observers this week is near four for those located north
of the equator and two for observers south of the equator. For morning
observers the estimated total hourly rates should be near fifteen for those
located in the northern hemisphere and seven for those viewing from 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. Morning
rates are slightly reduced due to moonlight during this period.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning October 6/7. 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 (very close to the current position) 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.

The Draconids (GIA) are predicted to peak on October 9 near 0430 Universal
Time. This corresponds to the evening hours of October 8 for those located
in the American longitudes. The radiant is located at 17:28 (262) +54, which
places it in southern Draco, two degrees northwest of the third magnitude
star Rastaban (Beta Draconis). This star is one of the four that form the
prominent head of Draco, also known as the "Lozenge". Expected rates are
always a guess but usually quite low. Due to the extreme northern
declination, this shower is only visible from the southern tropics
northward. The radiant is best placed just as it becomes dark during the
evening hours. At 20km/sec., the average Draconid is extremely 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 01:52 (028) +14. This
position lies in western Aries, five degrees south of the fourth magnitude
star Mesarthim (Epsilon Arietis). The Southern Taurid (STA) radiant lies at
02:00 (030) +08. This position lies in southeastern Pisces, six degrees
north of the fourth magnitude star Alrischa. 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. At 29 and 27 km/sec., the
average Taurid meteor travels slowly through the skies.

The Orionids (ORI) are just beginning to appear from a radiant located at
05:44 (86) +14. This position lies in extreme eastern Taurus, five degrees
northwest 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 one or two per hour At 64km/sec., the average
Orionid is swift.

The Delta Aurigids (DAU) are present in the morning skies in the second half
of September and early October. Maximum activity occurs on October 4 with an
average ZHR of two. Current rates will be most likely less than one per
hour. The radiant is located 06:00 (090) +49. This position lies in northern
Auriga, four degrees north of the second magnitude star Menkalinan (Beta
Aurigae). Note that in my last meteor outlook the position of this shower
was given for the 25th of September, not the 30th. The correct position for
the 30th is six degrees further east at 05:32 (083) +49. At 64km/sec., the
average Delta Aurigid is swift.

Sporadic rates have nearly 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 twelve random meteors during the last
hour before dawn from rural observing sites in the northern hemisphere.
During the first dark hour after the end of evening twilight, perhaps four
random meteors can be seen per hour. As seen from the southern hemisphere
late morning rates would now be near four per hour. During the first dark
hour after the end of evening twilight, perhaps two random meteors can be
seen per hour. Morning rates are slightly reduced due to moonlight during
this period.

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

Draconids (GIA)  17:28 (262) +54
Northern Hemisphere - <1   Southern Hemisphere - <1

Northern Taurid (NTA)  01:52 (028) +14
Northern Hemisphere - 1   Southern Hemisphere - 1

Southern Taurid (STA)  02:00 (030) +08
Northern Hemisphere - 1   Southern Hemisphere - 1

Orionids (ORI)  05:44 (86) +14
Northern Hemisphere - 1   Southern Hemisphere - 1

Delta Aurigids (DAU)  06:00 (090) +49
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