Meteor Activity Outlook for August 25-31, 2012

During this period the moon reaches its full phase on Friday August 31st. At
this time the moon will be located opposite the sun and will be above the
horizon all night long. This weekend the waxing gibbous moon will set during the
early morning hours, allowing a few hours of dark skies between moon set and the
start of morning twilight in which good activity can be observed. The estimated
total hourly meteor rates for evening observers this week is near four for
observers located at mid-northern latitudes and three for observers in
mid-southern latitudes. For morning observers the estimated total hourly rates
should be near twenty from the mid-northern hemisphere and eight from the
mid-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 during this
period 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 August 25/26. 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 radiants are expected to be active this week:

The Kappa Cygnids (KCG) are winding down but still active from a wide radiant
located at 18:28 (268) +63. This position lies in a remote area of southern
Draco. The nearest bright star is third magnitude Aldib (Delta Draconis), which
lies seven degrees to the northeast. Some readers will notice that this position
is west of that given last week. The reason for this seemingly retrograde motion
is the different sub-centers of activity that appear within the large radiant
area during this month. Observers need not be strict with shower association for
this shower due to the wide radiant and these sub-centers of activity. Maximum
activity occurred on August 18th so current rates would be less than one per
hour no matter your location. With an entry velocity of 23 km/sec. most of these
meteors will appear to travel slower than average. The radiant is best placed
near 2300 Local Daylight Time (LDT) 11pm Local Daylight Time (LDT) when it lies
nearly overhead for much of the Northern
Hemisphere. Due to its high northern declination this activity is not well
seen from the southern hemisphere.

The large Antihelion (ANT) radiant is currently located at 23:00 (345) -05. This
position lies in northeastern Aquarius, four degrees northwest of the fourth
magnitude star Phi Aquarii. Due to the large size of this radiant, Antihelion
activity may also appear from eastern Capricornus, southern Pisces, southern
Pegasus, and western Cetus as well as Aquarius. This radiant is best placed near
0200 LDT, when it lies on the meridian and is located highest in the sky. Rates
at this time are expected to be near one per hour no matter your location. With
an entry velocity of 30 km/sec., the average Antihelion meteor would be of slow
velocity.

There is an active yet unnamed radiant located just east of the “circlet” of
Pisces this week. The exact location for Sunday morning is 23:48 (357) +06. This
lies in western Pisces between the fourth magnitude stars Omega and Iota
Piscium. Radiant drift per day averages 0.8 degree in right ascension and +0.4
in declination. This radiant is stronger than all but the Perseids so naked eye
verification should be fairly easy. This activity is present from August 6th
through September 6th with a maximum occurring on August 17th. With an entry
velocity of 41 km/sec., most activity from this radiant would be of average
velocities.

There is another active yet unnamed radiant located in southern Perseus active
only this weekend The exact location for Sunday morning is 03:52 (058) +36. This
position lies two degrees west of the fourth magnitude star Xi Persei. This is
the fourth most active radiant in the sky so rates would be near one per hour as
seen during the morning hours from the mid-northern hemisphere. This radiant is
not well placed for viewing south of the equator. With an entry velocity of 69
km/sec., most activity from this radiant would appear as swift meteors.

The Perseids (PER) peaked on Sunday August 12th, producing visible hourly rates
near 50 as seen from dark skies. They are still the most active radiant in the
sky but rates are now down to only 2-3 shower members per hour as seen from the
mid-northern hemisphere during the early morning hours. The current radiant is
located at 04:28 (067) +59. This position lies in a blank portion of southern
Camelopardlis, five degrees southeast of fourth magnitude star Beta
Camelopardalis. With an entry velocity of 61 km/sec., most activity from this
radiant would be swift.

The Aurigids (AUR) become active on August 25th but are very weak until the
morning of August 30th. Maximum occurs on August 31st when it becomes the most
active radiant in the sky. Unfortunately the full moon will spoil the display at
this time so only 1-2 shower members will be visible per hour as seen during the
morning hours from mid-northern latitudes. Very little activity would be visible
from the southern hemisphere. At maximum the radiant is located at 06:02 (091)
+39, which places it in eastern Auriga just two degrees north of third magnitude
Theta Aurigae. 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 three 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 two per hour during
the evening hours. Locations between these two extremes would see activity
between the listed figures. Evening rates are reduced due to to moonlight during
this period.

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