Meteor Activity Outlook for May 22-28, 2010

May is a fairly slow month for meteor activity.
The Eta Aquariids are very active the first two weeks of the month then fade as
the month progresses. The only other showers active this month are the weak Nu
Cygnids, the Eta Lyrids, and the Antihelion radiant. These will add only 1-2
meteors per hour to the total count. Sporadic rates are low but steady 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 full phase
on Thursday May 27th. At this time the moon lies opposite of the the sun and is in
the sky the entire night. Conditions are more favorable this weekend as the waxing
gibbous moon will set during the early morning hours allowing a couple hours of
darkness between moonset and the start of morning twilight. The estimated total hourly rates
for evening observers this week is near one for northern observers and two for
those viewing from south of the equator. For morning observers the estimated total
hourly rates should be near seven from the northern hemisphere and seventeen as seen
from the 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. Evening rates are 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 May 22/23. 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 showers are expected to be active this week:

The wide Antihelion (ANT) radiant is now centered at 16:56 (254) -23. This
area of the sky lies in southern Ophiuchus some seven degrees northeast of the first
magnitude orange star Antares (Alpha Scorpii). This radiant is best placed near 0200
local daylight time (LDT) when it lies on the meridian and is located highest in
the sky. Due to the large size of this radiant, any meteor radiating from eastern
Libra, northern Lupus, southern Ophiuchus, southern Serpens Cauda, western Sagittarius,
or Scorpius could be a candidate for this shower. Rates at this time should be near
one per hour as seen from the northern hemisphere and two per hour as seen from south
of the equator. With an entry velocity of 30 km/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 table below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.