(meteorobs) Meteor Activity Outlook for September 27-October 3, 2008

[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 observers located in the sporadic-poor southern
hemisphere this time of year.

During this period the moon reaches its new phase on Monday September 29th.
At this time the moon will be located near the sun and will not be visible
at night. Later in the period the waxing crescent moon will enter the
evening sky but set soon after the end of evening twilight. It will not
interfere with meteor observing no matter the hour. 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 for those located in the mid-northern
hemisphere (45 N) and ten 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.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning September 27/28. 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:

The center of the large Northern Taurid (NTA) radiant is now centered at
01:24 (021) +12. This position lies in eastern Pisces, three degrees
southwest of the fourth magnitude star Eta Piscium. The center of the large
Southern Taurid (STA) radiant lies at 01:36 (024) +07. This position also
lies in eastern Pisces, three degrees southwest of the fourth magnitude star
Eta 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 less difficult to distinguish those meteors traveling east
or west. These radiants are best placed near the meridian at 0200. At 29 and
27 km/sec., the average Taurid meteor travels slowly through the skies.

The Delta Aurigids (DAU) are present in the morning skies in the second half
of September and early October. Maximum activity occurs on October 3rd with
an average ZHR of two. Current rates will be most likely near one per hour
as seen from the northern hemisphere and less than one as seen from the
south of the equator. The radiant is currently located 05:24 (081) +49. This
position lies in northwestern Auriga, three degrees north of the zero
magnitude star Capella (Alpha Aurigae). At 64km/sec., the average Delta
Aurigid is swift.

Sirko Molau's study of video radiants has shown an active radiant located in
Orion during this period. The September Alpha Orionids (AOR) peak on
September 27th with a radiant located near 05:24 (081) +07. The area of the
sky is located in northwestern Orion near the bright star Bellatrix (Gamma
Orionis). Activity is more than a ZHR of one between September 24th and the
30th. This radiant was one of the strongest new showers detected in the
video survey. Meteors from this radiant are not visible during the evening
hours as Orion lies beneath the horizon during this time. The radiant gains
altitude during the morning hours and is most favorably located near 0600
LDT when it lies highest above the horizon. Due to its location near the
celestial equator, activity is visible nearly everywhere. Tropical locations
are favored as the radiant passes overhead. Hourly rates this week would be
near one no matter your location. With an entry velocity of 59 km/sec., most
members of the September Alpha Orionids would possess a swift velocity.

During 2005 and 2006 a shower of bright meteors has occurred on October 5th
and 6th, radiating from near the Draco/Camelopardalis border. The 2007
display was missed due to moonlight and clouds. The October Camelopardalids
(OCT) peak for only a few hours but shower members are bright and should be
easy to observe. The 2008 display is predicted to occur near 14 UT on
October 5th, which corresponds to 0700 PST. It is daylight at this time from
the USA's west coast but observers along the Pacific coast of Canada and
Alaska can view at this time. The last hour before dawn may provide some
activity as seen from the western USA and Canada. The estimated position of
the radiant on the 5th is 10:48 (162) +79. The nearest easy star to identify
the radiant is 4th magnitude SAO1551. Polaris (Alpha Ursae Minoris) lies 12
degrees to the north. This area of the sky is circumpolar from nearly the
entire northern hemisphere. The radiant lies highest above the horizon in a
dark sky at both dusk and at dawn. Due to this unusual situation this shower
would be totally invisible from the southern hemisphere. With an entry
velocity of 47 miles per second most members of the October Camelopardalids
would be of medium-swift velocity. Shower members should be seen from
October 1-10, but at very low numbers away from the peak hour on the 5th.

As seen from the mid-northern hemisphere (45N) one would expect to see
approximately fifteen 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.

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.

Northern Taurid (NTA)   01:24 (021) +12   Velocity - 29km/sec
Hourly Rates: Northern Hemisphere - 2   Southern Hemisphere - 2

Southern Taurid (STA)   01:36 (024) +07   Velocity - 27km/sec.
Hourly Rates: Northern Hemisphere - 3   Southern Hemisphere - 3

Delta Aurigids (DAU)   05:24 (081) +49   Velocity - 64km/sec.
Hourly Rates: Northern Hemisphere - 1   Southern Hemisphere - <1

September Alpha Orionids (AOR)   05:24 (081) +07   Velocity - 59km/sec.
Hourly Rates: Northern Hemisphere - 1   Southern Hemisphere - 1

October Camelopardalids  (OCT)   10:48 (162) +79   Velocity - 47km/sec.
Hourly Rates: 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#X2008

Clear Skies!
Robert Lunsford
American Meteor Society