(meteorobs) Meteor Activity Outlook for May 30-June 5, 2009

[Robert Lunsford]

June is another slow month for meteor activity. There are no major showers
active in June and only the Antihelion source can be counted on for
continuous activity. Even the Antihelion is located so far south this time
of year that rates rarely exceed two per hour as seen from the northern
hemisphere. Sporadic rates reach their nadir in June as seen from the
mid-northern hemisphere (45 N). Sporadic rates seen from the mid-southern
hemisphere (45 S) continue to rise this month toward a maximum in July.

During this period the moon reaches its first quarter phase on Sunday May
31. At this time the moon lies ninety degrees east of the sun and is above
the horizon during the evening hours. It sets near 0100 local daylight time
(LDT) and the remainder of the night is free of interfering moonlight. Later
in the period the waxing gibbous moon will set later and later, reducing the
window of opportunity for viewing under truly dark conditions. The estimated
total hourly rates for evening observers this week is near two as seen from
the northern hemisphere and three for those situated south of the equator.
For morning observers the estimated total hourly rates should be near seven
for those located in the mid-northern hemisphere (45 N) and seventeen for
those viewing from the mid-southern hemisphere (45 S). Locations between
these two extremes would see activity between the listed figures. 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
moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning May 30/31. 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 shower is expected to be active this week:

The wide Antihelion (ANT) radiant is now centered at 17:32 (263) -23. This
area of the sky lies in extreme southeastern Ophiuchus, three degrees
northeast of the third magnitude star Theta Ophiuchi. This radiant is best
placed near 0200 LDT when it is located on the meridian and lies highest in
the sky above the horizon. Due to the large size of this radiant, any meteor
radiating from southern Ophiuchus,northern Scorpius, western Sagittarius, or
southern Serpens Cauda could be a candidate for this shower. Rates at this
time should be near two per hour as seen from the southern hemisphere and
one as seen from north of the equator. With an entry velocity of 30km/sec.,
the average Antihelion meteor would be of medium-slow speed.

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

The list below presents a summary of the expected activity this week. Rates
and positions are exact for Saturday night/Sunday morning but may be used
all week.

Antihelion (ANT) - 17:32 (263) -23    Velocity - 30km/sec.
Hourly Rates - Northern Hemisphere 1 - Southern Hemisphere - 2

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2009

Clear Skies!
Robert Lunsford
American Meteor Society