Meteor Activity Outlook for September 21-27, 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 separate. 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 full
phase on Wednesday September 26. At this time the moon is located opposite the
sun and is in the sky all night long. This weekend a small window of opportunity
exists between moonset and the start of morning twilight. The estimated total
hourly rates for evening observers this week is near three 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. Rates are reduced due to moonlight during this period.

The radiant positions and rates listed below are exact
for Saturday night/Sunday morning September 22/23. 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 Antihelion (ANT) radiant is now centered at 00:52 (013) +06. This area
of the sky is located in a southern Pisces just one degree south of the fourth
magnitude star Delta 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 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 05:00 (075) +49. This position lies in northwestern Auriga,
four degrees northwest of the zero magnitude star Capella (Alpha Aurigae). At
64km/sec., the average Delta Aurigid is swift.

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
approximately eight 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 two 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 one random meteor
can be seen per hour. Rates are reduced due to moonlight during this period.