Meteor Activity Outlook for September 3-9, 2011

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 Sunday September
4th. At this time the moon will lie ninety degrees east of the sun and will set
near midnight local daylight time (LDT) as seen from mid-northern latitudes.
Next week the waxing gibbous moon will set later during the morning hours but
still allowing meteor observers a window of opportunity to view under dark
conditions between moon set and the start of morning twilight . The estimated
total hourly rates for evening observers this week is near three as seen from
the northern hemisphere and two as seen from the southern hemisphere. For
morning observers the estimated total hourly rates should be near fifteen as
seen from mid-northern latitudes and eight from mid-southern latitudes. 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 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
3/4. 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 wide Antihelion (ANT) radiant is now centered at 23:36 (354) -01. This area
of the sky lies in western Pisces, just below the faint circle of stars known as
the “circlet”. This radiant is best placed near 0200 LDT, when it lies on the
meridian and is located highest in the sky. Due to the large size of this
radiant, any meteor radiating from eastern Aquarius, western Pisces,
northwestern Cetus, or southern Pegasus could be a candidate for this shower.
Rates at this time should be near one per hour no matter your location. With an
entry velocity of 30 km/sec., the average Antihelion meteor would be of
medium-slow speed.

Studies of the IMO’s video database by Sirko Molau and Juergen Rendtel has
revealed a new radiant active in Perseus this time of year. The September Iota
Cassiopeiids (SIC) are active from September 4th through the 13th with maximum
activity occurring on the 12th. The radiant position is currently located at
02:33 (038) +57. This position lies just over the border of Cassiopeia in
Perseus, four degrees northeast of the fourth magnitude star Eta Persei. 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 10th. The radiant position is
currently located at 02:56 (044) +41. This position lies in southwestern
Perseus, only two degrees west 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 currently less than one per hour but will
increase to 1-3 per hour at maximum. This shower experienced an outburst in 2008
with ZHR’s near 25 for a short time. Many bright meteors were produced during
this outburst with the brightest estimated at magnitude -8. With an entry
velocity of 66 km/sec., most activity from this radiant would be swift. This
activity is visible from the tropical regions of the southern hemisphere, but
further south the radiant becomes too low in the sky to produce much activity.

Many radiants in the region of Eridanus have been suspected this time of year.
Recent studies of the IMO’s video database by Sirko Molau and Juergen Rendtel
has verified a radiant active in Eridanus from September 3rd through the 24th
with maximum activity occurring on the 7th. The Nu Eridanid (NUE) radiant is
currently located at 04:20 (065) -01. This position lies in a remote region of
northeastern Eridanus. The nearest bright star is Rigel (Beta Orionis), which
lies twelve degrees to the southeast. The radiant is best placed during the last
hour before the start of morning twilight. Rates may be close to two per hour
this weekend and early next 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.

The last of the Aurigids (AUR) can be seen this weekend from a radiant located
at 06:21 (095) +40. This position lies in central Auriga, two degrees northeast
of the third magnitude Theta Aurigae. The radiant is best placed during the last
hour before the start of morning twilight when it lies highest in a dark sky.
Hourly rates this weekend will be very low, less than one per hour no matter
your location. With an entry velocity of 67 km/sec., most activity from this
radiant would be swift.

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 five
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 by moonlight.

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