Meteor Activity Outlook for August 31-September 6, 2007

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 is
impossible to seperate. Therefore the antihelion radiant will be excluded from the
list 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 last quarter
phase on Tuesday September 4. At this time the half illuminated moon is located
ninety degrees west of the sun and rises near 0100 local daylight time. The estimated
total hourly rates for evening observers this week is near four for those located
north of the equator and one for observers south of the equator. For morning observers
the estimated total hourly rates should be near ten for those located in
the northern hemisphere and five 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 reduced by moonlight.

The radiant positions and rates listed below are exact
for Saturday night/Sunday morning September 1/2. 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 the IMO’s video database has led to the discovery of an
active radiant in Ursa Minor this week. The shower peaks on September 1 from a
radiant located at 17:24 (261) +83. This position lies in the handle of the Little
Dipper just west of the fourth magnitude star Epsilon Ursae Minoris. The radiant
is best placed near 2000 (8pm) local daylight time, when it lies highest in the
sky. Current rates would mostly likely be less than one per hour, but this
is uncertain. With an entry velocity of 38km/sec., activity from this radiant
would be of medium velocity.

The Antihelion (ANT) radiant is now centered at 23:28 (352) -02. This area
of the sky is located in a western Pisces, three degrees south of the faint star
Kappa Piscium. This radiant is best placed near 0200 LDT, when it lies on the
meridian and is highest in the sky. Rates at this time should be near two per hour
regardless of your location. With an entry velocity of 30 km/sec., the average
antihelion meteor would be of medium-slow speed.

The Alpha Aurigids (AUR) are predicted to reach maximum activity at 11:37
Universal Time on September 1. This timing favors western North America and the
eastern pacific area including Hawaii. Other areas are expected to see little from
this radiant. The radiant position is usually located near 05:36 (084) +42, which
is located in central Auriga, five degrees southeast of the brilliant zero
magnitude yellow star Capella (Alpha Aurigae). Near the time of maximum the radiant
may be slightly different from this position but the swift meteors from Auriga
will be easy to differenciate from other activity that night. This radiant is
circimpolar 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. At 66 km/sec.,
these meteors are swift, often exhibiting persistent trains. The moon will be a
major factor on September 1, obscuring the faint meteors. Finding dry, transparent
skies and facing away from the moon will be the best way overcome the lunar glare.

Sirko Molau’s study of the IMO’s video database has led to the discovery of an
active radiant in eastern Auriga this week. The shower peaks on September 1 from a
radiant located at 07:24 (111) +39. This position lies six degrees northwest of
the second magnitude star Castor (Alpha Geminorum). The radiant is best placed
just before dawn when it lies highest in a dark sky. Current rates would mostly
likely be less than one per hour, but this is uncertain. With an entry velocity
of 39km/sec., most activity from this radiant would be of medium velocities.

Sporadic rates are slowly rising for observers in the northern hemisphere and
falling steadily for those located south of the equator. One would expect to see
perhaps seven 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 three 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 reduced by moonlight.