Meteor Activity Outlook for September 11-17, 2010

September offers longer nights in the northern
hemisphere that tend to be less hazy than those experienced in mid-summer. In the
sky, no major showers are visible from either hemisphere but the northern
hemisphere enjoys the advantage of higher sporadic rates. Most of the shower
activity this month is produced from the Perseus-Aurigid complex active this time
of year. These showers rarely produce more than five meteors per hour but still
manage to produce most of the shower activity seen this month. Unfortunately the
Perseus-Aurigid complex lies too low in the northern sky for southern hemisphere
observers to view very well. Video studies have shown that the Southern Taurids
are visible as early as September 7th therefore after this date the Antihelion
radiant will no longer be listed until the Taurid showers end in December. The
Antihelion meteors are still active but their radiant is superimposed upon that
of the more numerous Taurids, therefore it is impossible to properly separate
these meteors. Observers in the southern hemisphere suffer from some of their
lowest rates of the year this month. The Southern Taurid radiant is not too badly
placed so observers south can expect to see a little of this activity this month.

During this period the moon reaches its first
quarter phase on Wednesday September 15th. At this time the moon will be located
ninety degrees east of the sun and will set near 0100. This weekend the waxing
crescent moon will set during the late evening hours and will not interfere with
meteor observing during the prime morning hours. The estimated total hourly rates
for evening observers this week is near three from the northern hemisphere and
two for observers south of the equator. For morning observers the estimated total
hourly rates should be near twenty from the northern hemisphere and ten as seen
from the southern hemisphere. 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. Evening rates are reduced this week due
to moonlight.

The radiant (the area of the sky where meteors appear
to shoot from) positions and rates listed below are exact for Saturday night/Sunday
morning September 11/12. 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:

Recent video studies by Sirko Molau and Juergen Rendtel have revealed that activity
from the Southern Taurids (STA) is actually detectable beginning on September 7th.
So from now until December 10th, the Taurid radiants will replace the Antihelion
source since they overlap and cannot be separated. The large Southern Taurid
radiant is now centered at 00:32 (008) +04. This area of the sky lies on the
Pisces/Cetus border, five degrees southwest of the fourth magnitude Delta Piscium.
The radiant is large so that any meteor from Pisces, northern Cetus, northeastern
Aquarius, or southeastern Pegasus could be a candidate for this shower. This radiant
is best placed near 0200 LDT when it lies on the meridian and is located highest in
the sky. Maximum activity is not until October 10th so current rates should be near
three no matter your location. With an entry velocity of 29 km/sec., the average
Southern Taurid meteor would be of medium-slow speed.

Studies of the IMO’s vast video database by Sirko Molau and Juergen Rendtel has
revealed a radiant active in Cassiopeia this time of year. The September Iota
Cassiopeiids (SIC) are active from September 4th through the 13th with maximum
activity occurring on the 11th. The radiant position is currently located at 02:28
(037) +66. This position lies in eastern Cassiopeia, five degrees northeast of the
third magnitude star Segin (Epsilon Cassiopeiae). The radiant is best placed near
0500 LDT, when it lies highest above the horizon. Rates throughout the activity
period are expected to remain less than one per hour. With an entry velocity
of 50 km/sec., most activity from this radiant would be swift. Due to the high
northern declination (celestial latitude) meteors from this shower are not well
seen from the southern hemisphere.

The September Epsilon Perseids (SPE) are active from September 5th through the 13th
with maximum activity occurring on the 9th. The radiant position is currently
located at 03:16 (049) +41. This position lies in southwestern Perseus, only two
degrees east of the famous eclipsing variable star known as Algol (Beta Persei).
The radiant is also best placed near 0500 LDT, when it lies highest above the
horizon. Rates are expected to be less than one per hour. With an entry velocity
of 66 km/sec., most activity from this radiant would be swift. This activity is
visible down to the tropical regions of the southern hemisphere. While watching
for the September Epsilon Perseids I would suggest also watching for any activity
from the original IMO September Perseid radiant. There have been reports of
activity from this source this year including an estimated -11 fireball on September
9th. The radiant is active from a position of 04:08 (062) +47. This position is
located in eastern Perseus near the fourth magnitude star Upsilon Persei. Activity
is expected through September 17th.

Many radiants in the region of Eridanus have been suspected this time of year.
Recent studies have verified a radiant active in Eridanus from September 3rd
through the 24th with maximum activity occurring on the 6th. The Nu Eridanid
(NUE) radiant is currently located at 04:40 (070) +03. This position lies in
a remote region of northeastern Eridanus, a dozen degrees due south of the bright
first magnitude orange star Aldebaran (Alpha Tauri). The radiant is best placed
near 0500 LDT, when it lies highest above the horizon in a dark sky. Rates should
be 1-2 per hour this week. With an entry velocity of 68 km/sec., most activity
from this radiant would be swift. With the radiant lying close to the celestial
equator, these meteors are seen equally well from both hemispheres.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately
fourteen sporadic meteors per hour during the last hour before dawn as seen from
rural observing sites. Evening rates would be near two 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. Evening
rates are reduced due to moonlight.

The table below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.