Meteor Activity Outlook for August 11-17, 2012

During this period the moon reaches its new phase on Friday August 17th. At this
time the moon will be located near the sun and will not be visible at night.
This weekend the waning crescent moon will rise during the early morning hours,
giving off some glare in the eastern sky. You can compensate for this by facing
away from the moon in another direction where the sky should be largely
unspoiled by moonlight. The estimated total hourly meteor rates for evening
observers this week is near six 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 sixty from the mid-northern
hemisphere and twenty 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.
Morning rates are slightly 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 August 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 radiants are expected to be active this week:

The Kappa Cygnids (KCG) are active from a wide radiant located at 19:00 (285)
+51. This position lies on the Cygnus/Draco border, eight degrees northwest of
the third magnitude star Rukh (Delta Cygni). Maximum activity occurs on August
17th so current rates would be one per hour from the northern hemisphere and
less than one shower member per hour from south of the equator. 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 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 22:08 (332) -09. This
position lies in central Aquarius, two degrees southwest of the fourth magnitude
star Theta Aquarii. Due to the large size of this radiant, Antihelion activity
may also appear from eastern Capricornus, western Pisces, and southwestern
Pegasus 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 two per hour as seen from the northern hemisphere and three
per hour as seen from south of the equator. With an entry velocity of 30
km/sec., the average Antihelion meteor would be of slow velocity.

The Delta Aquariids (SDA) are still active from a radiant located at 23:28 (352)
-13. This position is located in east-central Aquarius, four degrees southeast
of the naked eye triple star known as Psi Aquarii. Current hourly rates would be
one from the northern hemisphere and two from south of the equator. 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 Eta Eridanids (ERI) are active from July 24 through August 18 with maximum
activity occurring on August 8. The current radiant position is 03:00 (045) -10,
which places it in western Eridanus, just one degree southeast of the fourth
magnitude star Eta Eridani. Current rates would be near one per hour no matter
your location. The radiant is best placed during the last hour before dawn, when
it lies highest in a dark sky. With an entry velocity of 66 km/sec., the average
Eta Eridanid meteor would be swift.

The Perseids (PER) peak on Sunday morning from a radiant located at 03:12 (048)
+58. This position lies near the intersection of Cassiopeia, Perseus, and
Camelopardalis. Gamma Persei lies four degrees to the southwest of the radiant.
The radiant is circumpolar north of 32 degrees north latitude but best placed
during the last hour before the start of morning twilight, when it lies highest
in a dark sky. Expected maximum rates, when the radiant is located highest in a
dark sky, are near forty per hour as seen from the northern hemisphere and ten
per hour as seen from tropical southern latitudes. Rates are slightly reduced
due to moonlight, as the 25 percent illuminated moon lies fairly close to the
radiant. Activity from this source is not visible south of 35 degrees south
latitude. With an entry velocity of 61 km/sec., most activity from this radiant
would be swift.

A new source found by the IMO video cameras to be active this time of year are
the Alpha Triangulids (ATR). This radiant has recently been found to be active
later than previously published, with the activity period ranging from July 25
through August 21 with maximum activity occurring on July 27. Current rates
would be less than one per hour, no matter your location. The radiant is
currently located at 03:16 (049) +37, which is actually situated in southern
Perseus, five degrees southeast of the famous variable star known as Algol (Beta
Persei). The radiant is best placed during the last hour before dawn, when it
lies highest in a dark sky. With an entry velocity of 67 km/sec., the average
Alpha Triangulid meteor would be swift.

As seen from the mid-northern hemisphere (45N) one would expect to see
approximately twelve sporadic meteors per hour during the last hour before dawn
as seen from rural observing sites. Evening rates would be near four per hour.
As seen from the mid-southern hemisphere (45S), morning rates would be near six
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. Morning rates are slightly 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.