Meteor Activity Outlook for September 18-24, 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 full
phase on Thursday September 23rd. At this time the moon will be located opposite
the sun and will rise as the sun sets and sets as the sun rises. This weekend the
waxing gibbous moon will set during the early morning hours and will allow a short
window of opportunity between moonset and morning twilight to view meteor activity
under dark conditions. The estimated total hourly rates for evening observers this
week is near two from the northern hemisphere and one for observers south of the
equator. For morning observers the estimated total hourly rates should be near
sixteen from the northern hemisphere and six 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 18/19. 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 center of the large Southern Taurid (STA) radiant lies at 00:56 (014)
+05. This position lies in southern Pisces, three degrees southeast of the
fourth magnitude star Delta Piscium. Since the radiant is so large, any meteor
from Pisces, western Cetus, or southwestern Pegasus could be a candidate for this
shower. The radiant is best placed near the meridian near 0200 LDT, but activity
may be seen all night long. Striking the atmosphere at 29 km/sec., the average
Southern Taurid meteor travels slowly through the skies. Rates this week should
be near two per hour no matter your location.

Many radiants in the region of Eridanus and Orion have been suspected this time
of year. Recent studies have verified a radiant active in Eridanus and moving on
into Orion from September 3rd through the 24th with maximum activity occurring on
the 6th. The Nu Eridanid (NUE) radiant is currently located at 05:00 (075) +06.
This position lies in western Orion, five degrees west of the second magnitude star
Bellatrix (Gamma Orionis). Old time observers may recall a radiant active in Orion
this time of year called the Sigma Orionids. This may be a verification of that
activity. The radiant is best placed near 0500 LDT, when it lies highest above the
horizon in a dark sky. Rates should less than one 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.