(meteorobs) Meteor Activity Outlook for May 5-11, 2006

[Robert Lunsford]

With the arrival of May, observers in the tropical areas of the world are
enjoying good views of the Eta Aquarids during the morning hours. The
Antihelion radiant moves from eastern Libra, through northern Scorpius and
into southern Ophiuchus during May. These areas of the sky are south of the
celestial equator, favoring observers watching from south of the equator.
Northern observers still suffer with low sporadic rates, especially during
the evening hours. This situation will not improve until mid-July, when
sporadic rates dramatically rise for northern observers. The overall meteor
activity is much like April, possibly slightly better in the south and
slightly worse in the north. The most favorable time to view meteor activity
this month would be during the first week of the month, when the Eta
Aquarids are near maximum activity.

During this period the moon will reach its first quarter phase on May 5. At
this time the moon will set near 0100, allowing the early morning hours to
be free of interfering moonlight. As the week progresses the waxing gibbous
moon will remain in the morning sky later and later. Near the end of this
period the nearly full moon will seriously hamper any attempt for successful
observing. The estimated total hourly rates for evening observers this week
is near one for observers in the northern hemisphere and two for those south
of the equator. For morning observers the estimated total hourly rates
should be near twenty for those in the northern hemisphere and thirty for
those south of the equator. 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.
Rates are reduced during the evening hours due to lunar interference.

The radiant positions listed below are exact for Saturday night/Sunday
morning May 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. 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 Antihelion (ANT) radiant is now centered at 15:56 (239) -20. This area
of the sky is located on the Libra- Scorpius border, ten degrees northwest
of the orange first magnitude star Antares (Alpha Scorpii). This radiant is
best placed near 0200 local daylight time when it lies on the meridian and
is highest in the sky. Rates at this time should be near two per hour for
those north of the equator and three per hour south of the equator. With an
entry velocity of 30 km/sec., the average Antihelion meteor would be of
medium-slow speed.

The Eta Lyrids (IAA) are produced by comet IRAS-Araki-Alcock, which passed
very close to the Earth twenty three years ago this May. Weak activity from
this radiant has been seen in most years from May 5 through May 17, with
maximum activity occurring on May 9. The current radiant position is located
at 19:04 (286) +44. This area of the sky is located in northeastern Lyra,
five degrees northeast of the zero magnitude star Vega (Alpha Lyrae). The
best time to view this activity is just before the start of morning
twilight, when the radiant lies highest in a dark sky. With an entry
velocity of 44 kilometers per second, a majority of these meteors will
appear to move at moderate speeds.

The Eta Aquarids (ETA) are particles from Halley's Comet, which last passed
through the inner solar system in 1986. Even though this is now twenty years
ago, material is still encountered every year in late April and throughout
most of May. We pass closest to Halley's orbit on May 6. At that time Eta
Aquarid rates can reach 30 shower members per hour as seen from the northern
tropical areas southward. The radiant is located at 22:36 (339) -01. This
area of the sky is located in central Aquarius, very close to the position
occupied by the fourth magnitude star Eta Aquarii. The best time to view
this activity is just before the start of morning twilight, when the radiant
lies highest in a dark sky. With an entry velocity of 66 kilometers per
second, a majority of these meteors will appear to move swiftly.

The Sporadic rates for the Northern Hemisphere are now nearing their annual
minimum activity. One would expect to see perhaps six random meteors per
hour during the last hours before dawn from rural observing sites. During
the evening hours perhaps one random meteor can be seen per hour. Sporadic
rates seen from the southern hemisphere are now increasing toward a
secondary maximum in July. One would see approximately eight random meteors
per hour during the late morning hours and two per hour during the evening.
Evening rates are reduced due to moonlight.

Antihelion (ANT) - 15:56 (239) -20 30
Northern Hemisphere 2 - Southern Hemisphere 3

Eta Lyrids (IAA) 19:04 (286) +44
Northern Hemisphere 1 - Southern Hemisphere <1

Eta Aquarids (ETA) 22:36 (339) -01
Northern Hemisphere 10 - Southern Hemisphere 20

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2006

Clear Skies!
Robert Lunsford
American Meteor Society