Meteor Activity Outlook for May 19-25, 2012

During this period the moon reaches its new phase on Sunday the 20th. At this
time the moon will be located near the sun and will not be visible at night. As
the week progresses the waxing crescent moon will enter the evening sky but will
not cause any problems with meteor observing. This is especially true for the
morning hours when the moon will be below the horizon. The estimated total
hourly rates for evening observers this week is near three for observers in the
northern hemisphere and four for those south of the equator. For morning
observers the estimated total hourly rates should be near seven as seen from
mid-northern latitudes and thirteen from mid-southern latitudes. 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 (the area of the sky where meteors appear
to shoot from) positions and rates listed below are exact for Saturday night/Sunday
morning May 19/20. 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 large Antihelion (ANT) radiant is currently located at 16:48 (252) -22. This
position lies in southwestern Ophiuchus, six degrees northeast of the bright
first magnitude orange star Antares (Alpha Scorpii). Due to the large size of
this radiant, Antihelion activity may also appear from Scorpius , Libra,
northern Lupus, western Sagittarius, southwestern Serpens Cauda, as well as
southern Ophiuchus . This radiant is best placed near 0200 LDT, when it lies on
the meridian and is located highest in the sky. Rates at this time should be
near two per hour as seen from the northern hemisphere and three as seen from
south of the equator. With an entry velocity of 30 km/sec., the average
Antihelion meteor would be of slow velocity.

The last of the Eta Aquariids (ETA) will be seen this weekend from a radiant
located at 23:12 (348) +04. This area of the sky is located in western Pisces,
two degrees northwest of the fourth magnitude star Gamma Piscium. The best time
to view this activity is during the hour before the start of morning twilight,
when the radiant lies highest in a dark sky. Hourly rates this weekend will most
likely be less than one per hour, no matter your location. With an entry
velocity of 67 kilometers per second, a majority of these meteors will appear to
move swiftly with a high percentage of the bright meteors leaving persistent
trains. Surprisingly, this shower produces very few fireballs.

As seen from the mid-northern hemisphere (45N) one would expect to see
approximately five sporadic meteors per hour during the last hour before dawn as
seen from rural observing sites. Evening rates would be near two per hour. As
seen from the mid-southern hemisphere (45S), morning rates would be near ten per
hour as seen from rural observing sites and three per hour during the evening
hours. Locations between these two extremes would see activity between the
listed figures.

The table below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.