(meteorobs) Meteor Activity Outlook for August 26 - September 1, 2005

[Robert Lunsford]

This upcoming period will see the moon reaching its last quarter phase on
Friday August 26.  This weekend will have a waning crescent moon and will
offer good views of the active morning sky as long as you keep the moon out
of your field of view. As the week progresses the moon will approach its new
phase and conditions will become even better. The estimated total hourly
rates for evening observers this week should be near three for Northern
Hemisphere observers and two for those located in the Southern Hemisphere.
For morning observers the estimated total hourly rates should be near twelve
for Northern Hemisphere observers and eight for those located in the
Southern Hemisphere. Morning rates are reduced due to moonlight. These rates
assume that you are watching from rural areas away from all sources of light
pollution. 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.

The radiant positions listed below are exact for Saturday night/Sunday
morning August 27/28. 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. 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.

These are the showers that may be observed this week:

The Kappa Cygnids (KCG) are active from a wide radiant located at 19:16
(289) +60. This position is located in southwestern Draco, eight degrees
south of the third magnitude star Delta Draconis. Current rates would be
near one shower member per hour as seen from the Northern Hemisphere. Due to
the high northerly declination this shower is not visible to a majority of
the Southern Hemisphere. A large percentage of these meteors are bright,
often fireball class meteors with brilliant colors. With an entry velocity
of 25 km/sec. most of these meteors will appear to travel slower than
average. The radiant is best placed near 2300 Local Daylight Time (11pm LDT)
when it lies nearly overhead for much of the Northern Hemisphere.

The North Iota Aquarids (NIA) are currently active from a radiant located at
22:24 (336) -05. This area of the sky is located in northern Aquarius, five
degrees south of the fourth magnitude star Gamma Aquarii. At 31 km/sec. the
NIA's are of average velocity. This radiant is most active near 0100 LDT
when it lies highest in the sky. Current hourly rates should be less than
one shower member per hour, no matter your location. This shower was
predicted to peak near August 19 with ZHR's of three.

The Anthelion radiant is now centered at 23:16 (349) -04. This area of the
sky is located in western Pisces, seven degrees south of the fourth
magnitude star Gamma Piscium. Since this radiant is large and diffuse, any
slow to medium speed meteor from western Pisces or eastern Aquarius could be
a candidate for this shower. The center of this area is best placed near
0200 local daylight time when it lies on the meridian and is highest in the
sky. At this time expect to see two shower members per no matter your
location.

Unlike most of the annual showers the antihelion source is produced by
debris from unknown objects orbiting in a direct motion like the earth.
These objects are most likely asteroids, which produce stony and metallic
debris whose density is much greater than material produced by comets. There
is also the possibility that some of this activity may be caused by the
"Jupiter family of comets", comets which have been altered by Jupiter's
gravity into much shorter orbits. This material collides with the earth on
the inbound portion of its orbit, before its closest approach to the sun.
Therefore we best see them just after midnight when we are facing the
direction from which this activity appears. The antihelion source is active
all year from an area of the sky nearly opposite that of the sun. The center
of this source will move approximately one degree eastward per day and
travels through many different constellations over the course of a year. It
may make sense to list these meteors as anthelions or "ANT" but a majority
of meteor organizations prefer that you list them from the constellation in
which the radiant is currently located or the constellation where the shower
reaches maximum activity. Those who send their reports to the International
Meteor Organization (IMO) should list these meteors as Southern Piscids
(SPI).

The Pi Eridanids (ERI) reach maximum activity on August 27 with a predicted
ZHR of four. Actual rates will more likely be one per hour unless you live
near the equator where the radiant passes overhead. The radiant position is
located at 03:32 (053) -15, which places it central Eridanus, five degrees
west of the third magnitude star Gamma Eridani. This area of the sky is
better placed for observers in the north tropical zone and areas further
south. It lies highest in the sky just before the onset on dawn. Like the
Perseids these meteors are swift if seen high in the sky far from the
radiant. I would also expect some trains from the brighter shower members.

The Gamma Doradids are an obscure minor shower listed among the radiants of
the Dutch Meteor Society. The peak activity is listed as August 30 with a
ZHR of five. The current radiant position lies at 04:00 (060) -50, which
places it in eastern Horologium some three degrees northwest of the third
magnitude star Gamma Dorado. Due to the extreme southern declination, this
shower is only visible from the northern tropics southward. The radiant is
best placed just before the start of morning twilight. At 41km/sec., these
meteors are of average velocity.

The Alpha Aurigids peak on the morning of September 1 with an average ZHR of
ten. The actual rates fluctuate greatly from one year to the next. The
radiant is located at 05:20 (08) +42, which places it in central Auriga some
four degrees south of the brilliant zero magnitude yellow star Capella
(Alpha Aurigae) . Due to the extreme northern declination, this shower is
only visible from the southern tropics northward. The radiant is best placed
just before the start of morning twilight, when it lies highest in the sky.
At 66km/sec., the average Alpha Aurigid is swift.  This shower produced
outbursts in 1986 and 1994, so with the moon out of the way this year I
encourage you to try to view this display.

The Sporadic rates for the Northern Hemisphere are now rising toward their
high plateau for the year. Observers can expect around six random meteors
per hour during the morning hours as seen from locations in the Northern
hemisphere. During the dark evening hours perhaps three random meteors can
be seen per hour north of the equator. Sporadic rates seen from the Southern
Hemisphere are falling and will bottom out in October. From south of the
equator one would expect to see approximately four random meteors per hour
during the late morning hours and two per hour during the evening. Morning
rates are reduced due to moonlight.

 Kappa Cygnids (KCG)   19:16 (289) +60
Hourly Rate = N. Hemisphere <1 - S. Hemisphere 0

Northern Iota Aquarids (NIA)   22:24 (336) -05
Hourly Rate = N. Hemisphere <1 - S. Hemisphere <1

Anthelion    23:16 (349) -04
Hourly Rate = N. Hemisphere 2 - S. Hemisphere 2

Pi Eridanids (ERI)   03:32 (053) -15
Hourly Rate = N. Hemisphere 1 - S. Hemisphere 1

Gamma Doradids (GDO)   04:00 (060) -50
Hourly Rate = N. Hemisphere <1 - S. Hemisphere 1

Alpha Aurigids (AUR)   05:20 (080) +42
Hourly Rate = N. Hemisphere 2 - S. Hemisphere <1

Clear Skies!
Robert Lunsford
American Meteor Society