Meteor Activity Outlook for August 30-September 5, 2008

September offers longer nights and cooler
temperatures in the northern hemisphere. In the sky, no major showers are visible
from either hemisphere but the northern hemisphere enjoys the advantage of higher
sporadic rates. The two recognized minor showers active in early September have
high northern declinations (celestial latitude) therefore are much better suited
to be viewed from locations north of the equator. Toward the end of the month the
antihelion radiant becomes entangled with the two Taurid radiants and it is
impossible to separate them. Therefore the antihelion radiant will be excluded
from the list from the last week of September until the end of the Taurid activity
period late in November. Observers in the southern hemisphere suffer from some of
their lowest rates of the year this month. The Taurid radiants are not too badly
placed so observers south of the equator can expect to see a little of this
activity toward the end of the month.

During this period the moon reaches its new
phase on Saturday August 30. At this time the moon will rise and set with the sun
and will not be visible at night. As the week progresses the waxing crescent moon
will enter the evening sky but will set during the early evening hours allowing
observers to view in dark skies the remainder of the night. The estimated total
hourly rates for evening observers this week is near three for those located in
the mid-northern hemisphere (45 N) and two for those viewing from the mid-southern
hemisphere (45 S). For morning observers the estimated total hourly rates should
be near eighteen for those located in the mid-northern hemisphere (45 N) and ten
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 August 30/31. 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 study of video radiants has shown an active radiant located in Ursa
Minor during this period. The September Ursid Minorids (SUM) peak on September
1st with a radiant located near 17:24 (261) +83. The area of the sky is located
in central Ursa Minor not far from Polaris, the North Star. This radiant is circumpolar
for areas north of 7 degrees north latitude. Interestingly enough, just 14 degrees
further south at 7 degrees south latitude, it cannot be seen at all! It reaches its
highest altitude above the horizon near 1900 (7pm) LDT. Most locations in the northern
hemisphere are not dark until an hour or two later so the period just as dusk settles
in would be the best time to try and observe this activity. Hourly rates would most
likely be less than one. With an entry velocity of 38 km/sec., most members of the
September Ursid Minorids would possess a medium velocity.

Another entry in Sirko Molau’s study of video radiants is located in Draco during
this period. The August Draconid (AUD) radiant lies near 19:28 (292) +65,
which is half-way between the bright stars Kochab (Beta Ursae Minoris and Deneb
(Alpha Cygni). This radiant is circumpolar for locations north of 25 degrees north
latitude. It reaches its highest altitude above the horizon near 2200 LDT, therefore
is best seen during the evening hours. Maximum activity occurred on August 27. Hourly
rates this weekend would most likely be less than one. The northern hemisphere is
heavily favored for viewing this activity. With an entry velocity of 30 km/sec.,
most members of the August Draconids would possess a medium-slow velocity. It
should be noted that if the Kappa Cygnid period is extended past August 25, the
radiant drift would be similar to the August Draconids.

The large Antihelion (ANT) radiant is now centered at 23:20 (350) -03.
This area of the sky lies on the Pisces/Aquarius border, three degrees northeast of
the fourth magnitude Phi Aquarii. Actually, the radiant is so large that any meteor
from northeastern Aquarius, western Pisces, or southwestern Pegasus could be a
candidate for this shower. This radiant is best placed near 0200 LDT when it lies
on the meridian and is highest in the sky. Hourly rates at this time should be near
three no matter your location. With an entry velocity of 30 km/sec., the average
Antihelion meteor would be of medium-slow speed.

The Aurigids (AUR) reach maximum activity on the morning of August 31st. The
radiant is located near 05:36 (084) +42. This position is located in central Auriga,
four degrees southeast of the brilliant zero magnitude yellow star Capella (Alpha
Aurigae). This radiant is circumpolar north of 48 degrees north latitude. For areas
further south in the northern hemisphere, the radiant rises during the late evening
hours. From south of the equator the radiant will rise during the late morning hours
(if at all) depending on your southern latitude. Regardless of location the radiant
is best placed during the last dark hour before morning twilight when it lies highest
in the sky. Hourly rates on Monday morning are expected to be near five. Unlike last
year, no outburst is expected from this shower. At 66 km/sec., these meteors are
swift, often exhibiting persistent trains.

The Southern September Lyncid (SSL) is another shower discovered by Sirko
Molau in his study of video radiants. This shower is active from August 28th through
September 5th and peaks on the morning of September 1st. The radiant actually lies
in extreme eastern Auriga, just over the border from Lynx. This position also lies six degrees north
of the famous double star Castor (Alpha Geminorum). The radiant rises near 0100 LDT
and reaches its highest altitude above the horizon near 0900 LDT. Since this is
during daylight hours the best time to view activity from the Southern September
Lyncids would be during the last dark hour before dawn. The much stronger Aurigids
are active the same night and care must be taken to avoid confusing the two showers.
Both showers produce swift meteors but the Aurigids would be far more numerous. If
any observer is serious about seeing any of this activity they should include both
radiants within their field of view. Viewing toward the north would also allow the
monitoring of the September Ursa Minorids. With an entry velocity of 52km/sec.,
most members of the Southern September Lyncids would move swiftly

As seen from the mid-northern hemisphere (45N) one would expect to see approximately
thirteen Sporadic meteors per hour during the last hour before dawn as seen from
rural observing sites. Evening rates would be near three per hour. As seen from the
mid-southern hemisphere (45S), morning rates would be near six per hour as seen
from rural observing sites and two 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.