(meteorobs) Meteor Activity Outlook for May 25-31, 2007

[Robert Lunsford]

May provides the peak of the Eta Aquarid meteor shower. This is the
strongest shower visible from the southern hemisphere but unfortunately this
year glare from the waning gibbous moon will obscure all but the brightest
meteors. The much weaker Eta Lyrids peak on May 9 under slightly better
conditions. Sporadic rates seen in the northern hemisphere are nearing the
nadir of their activity curve. The lowest rates are observed in June. On a
positive note, rates seen from the southern hemisphere are increasing toward
a July maximum.

During this period the moon waxes from slightly more than half illuminated
to nearly full. This weekend the waxing gibbous moon will set during the
early morning hours and will allow an observer a short time to view the
meteor activity in dark skies before the start of morning twilight. The
estimated total hourly rates for evening observers this week is near one for
those located north of the equator and two for observers south of the
equator. For morning observers the estimated total hourly rates should be
near seven for those located in the northern hemisphere and eighteen for
those viewing from 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. Evening rates are reduced due to the bright moon.

The radiant positions listed below are exact for Saturday night/Sunday
morning May 26/27. 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. Doing this 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 Antihelion (ANT) radiant is now centered at 17:12 (258) -23. This area
of the sky is centered in southeastern Ophiuchus, three degrees northwest of
the third magnitude star Theta Ophiuchi. This radiant is best placed near
0200 LDT, when it lies on the meridian and is highest in the sky. Rates at
this time should be near one per hour as seen in the northern hemisphere and
three per hour for those located south of the equator. With an entry
velocity of 30 km/sec., the average antihelion meteor would be of
medium-slow speed.

Sporadic rates are bottoming out for observers in the northern hemisphere
and slightly rising for those located south of the equator. One would expect
to see perhaps six random meteors during the last hour before dawn from
rural observing sites located in the northern hemisphere. During the first
dark hour after the end of evening twilight, perhaps one random meteor can
be seen per hour. Sporadic rates increase as the night progresses so rates
seen near midnight would be near three per hour. Late morning sporadic rates
seen from the southern hemisphere are now near fifteen per hour from rural
observing sites. During the first dark hour after the end of evening
twilight, perhaps two random meteors can be seen per hour, increasing to
eight by midnight. Evening rates are reduced due to the bright moon.

Antihelion (ANT) - 17:12 (258) -23
Northern Hemisphere - 1   Southern Hemisphere - 3

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2007

Clear Skies!
Robert Lunsford
American Meteor Society