(meteorobs) Meteor Activity Outlook for September 7-13, 2007

[Robert Lunsford]

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 new phase on Tuesday September 11.
At this time the moon is located close to the sun in the sky and is
invisible at night. 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 twenty for those located in the northern
hemisphere and six 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.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning September 8/9. 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 23:56 (359) +01. This area
of the sky is located in a western Pisces, three degrees east of the faint
star Lambda 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 September Perseids (SPE) peak on the morning of September 9 with an
average ZHR of six. The radiant is located at 03:56 (059) +47, which places
it in central Perseus, three degrees southeast of the third magnitude star
Delta Persei. The radiant is best placed in the sky just before the start of
morning twilight, when it lies highest above the horizon. At 64km/sec., the
average September Perseid is swift.

Sirko Molau's study of the IMO's video database has led to the discovery of
an active radiant in Lynx this week. The shower peaks on September 13
from a radiant located at 07:36 (114) +56. The radiant is best placed just
before the start of  morning twilight when it lies highest in a dark sky.
Current rates would most likely be less than one per hour, but this is 
uncertain.
With an entry velocity of 53km/sec., activity from this radiant would be of
medium-swift velocity.

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 fourteen 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 one random meteor can be seen per
hour.

Antihelion (ANT) - 23:56 (359) +01
Northern Hemisphere - 2   Southern Hemisphere - 2

September Perseids (SPE) 03:56 (059) +47
Northern Hemisphere - 3   Southern Hemisphere - <1

Lyncids (LYN)  07:36 (114) +56
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