Meteor Activity Outlook for August 6-12, 2011

During this period the moon reaches its first quarter phase on Saturday August
6th. At this time the moon will lie ninety degrees east of the sun and will set
near 0100 local daylight time (LDT) for observers located in the mid-northern
latitudes. Next week the waxing gibbous moon will enter the morning sky and will
reduce the observing window for dark sky viewing with each passing night. The
estimated total hourly rates for evening observers this week is near five 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 twenty
eight from mid-northern latitudes and seventeen 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 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 August 6/7. 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:

Activity from the August Draconids (AUD) can be first detected near August 11th
from a radiant located at 18:00 (270) +61. This position lies in southern Draco,
close to the second magnitude star Eltanin (Gamma Draconis). Maximum activity is
not predicted until August 21st so current rates would be low, less than one per
hour. With an entry velocity of 23 km/sec. most of these meteors will appear to
move slowly. The radiant is best placed near 2200 Local Daylight Time (10pm LDT)
when it lies highest in the sky. Due to its high northern declination this
shower is not well seen from the southern hemisphere.

The Kappa Cygnids (KCG) are active from a wide radiant located in northern Lyra,
southern Draco, and northwestern Cygnus. The strongest areas seem to vary year
to year but the current mean value lies near 18:47 (282) +46. This location lies
in northern Lyra, seven degrees northeast of the brilliant star Vega (Alpha
Lyrae). Maximum activity is now predicted to occur on August 14th. 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 LDT (11pm 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. Of the few meteors seen
from this source, several of them have been of fireball class brightness.

The Alpha Capricornids (CAP) are active from a wide radiant located at 20:40
(310) -08. This position lies near the area where Capricornus, Aquarius, and
Aquila meet. This position lies eight degrees northeast of the third magnitude
double star Alpha Capricornii. The radiant is best placed near 0100 local
daylight time (LDT), when it lies on the meridian and is highest in the sky.
Maximum activity occurred on July 30th so current rates should be less than one
as seen from the northern hemisphere and one per hour from the southern. Don’t
confuse these meteors with the antihelion meteors, which have a radiant just to
the east. Both radiants need to be in your field of view to properly sort these
meteors. With an entry velocity of 25 km/sec., most activity from this radiant
would be slow, a bit slower than the antihelions. This radiant is well seen
except for far northern latitudes where it remains twilight all night long and
the radiant does not rise as high into their sky.

The wide Antihelion (ANT) radiant is now centered at 21:48 (327) -12. This area
of the sky lies in eastern Capricornus, three degrees north of the third
magnitude star Deneb Algedi (Delta Capricorni). 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 Capricornus, Aquarius,
or southwestern Pegasus could be a candidate for this shower. Rates at this time
should be near one per hour as seen from the northern hemisphere and two per
hour as seen from south of the equator. With an entry velocity of 30 km/sec.,
the average Antihelion meteor would be of medium-slow speed.

The Delta Aquariids (SDA) reached maximum activity on July 30th. Current hourly
rates are near two per hour as seen from the northern hemisphere and three per
hour as seen from south of the equator. The radiant is currently located at
23:09 (347) -14. This position lies in central Aquarius, three degrees northeast
of the third magnitude star Delta Aquarii. The radiant is best placed near 0300
LDT, when it lies highest in the sky. With an entry velocity of 42 km/sec., most
activity from this radiant would be of average velocities.

The Piscids Austrinids (PAU) are a minor shower not well seen from the northern
hemisphere. This radiant is active from July 15 through August 10. Maximum
activity occurred on July 28 when the zenith hourly rate (ZHR) may reach five.
These rates are only seen from the southern hemisphere where the radiant passes
overhead. From mid-northern latitudes, rates of one per hour at maximum are
usually seen. The radiant is currently located at 23:18 (350) -27. This position
lies in extreme northwestern Sculptor, four degrees northeast of the first
magnitude star Fomalhaut (Alpha Piscis Austrinus). The radiant is best placed
near 0300 LDT, when it lies highest in the sky. With an entry velocity of
35km/sec., most activity from this radiant would be of average velocities.

Studies by Sirko Molau and Juergen Rendtel of the IMO’s video data have revealed
an active radiant in the constellation of Pisces this time of year. The August
Piscids (AUP) are active from August 2nd through the 9th with maximum activity
occurring on the 4th. On the 4th, the radiant is located at 00:40 (010) +19.
This area of the sky lies in a remote area of central Pisces, five degrees
northeast of the second magnitude star Algenib (Gamma Pegasi). Interestingly, if
one were to continue the radiant drift for the July Pegasids into August, it
would closely match that of the August Piscids. This radiant is best placed
during the last dark hour before dawn, when it lies highest above the horizon in
a dark sky. Rates at this time should be less than one no matter your location.
With an entry velocity of 66 km/sec., the average August Piscid meteor would be
of swift speed.

The Perseids (PER) are active from a radiant located at 02:38 (040) +56. This
position lies in northern Perseus, just west of the fourth magnitude star Eta
Persei. 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
during the late morning hours would be near ten as seen from the northern
hemisphere . As the week progresses the rates will increase as we approach the
August 13 maximum. Unfortunately the dark viewing window of opportunity
decreases as the moon waxes and the moon sets later with each passing night.
Activity from this source is poorly seen from the southern hemisphere and not
visible at all south of 40 degrees south latitude. With an entry velocity of 61
km/sec., most activity from this radiant would be swift.

While viewing the Perseids through the years, many observers have reported
noticing weak activity from the area of Cetus and Eridanus. During their studies
of the IMO’s video database, Sirko Molau and Juergen Rendtel discovered an
active radiant in this area. The Eridanids (ERI) are active from August 4th
through the 18th with maximum activity occurring on the 9th. Hourly rates could
reach 2-3 per hour at maximum. The radiant is currently located at 02:53 (043)
-12. This area of the sky is located in extreme western Eridanus, between the
faint stars Pi and Eta Eridani. This radiant is best placed during the last hour
before dawn when it lies highest in a dark sky. With an entry velocity of 64
km/sec., the average Eridanid meteor 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 seven 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 this week 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.