Meteor Activity Outlook for April 17-23, 2010

Meteor activity picks up a bit during April as two major showers
are active during the month. The first of these, the Lyrids, are active from the 16th through the
25th, with a pronounced maximum on the 22nd. The Eta Aquariids start appearing near the 28th and
reach maximum activity during the first week in May. 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) rise this month toward a maximum in July.

During this period the moon reaches its first quarter phase on
Wednesday April 21st. At this time the moon lies ninety degrees east of the sun and sets near 0100
local daylight time (LDT), depending on your location. This weekend the waxing crescent moon
will set shortly after the end of evening twilight and will not cause any interference to meteor
observers. The estimated total hourly rates for evening observers this week is near two for
northern observers and three for those viewing from south of the equator. For morning observers the
estimated total hourly rates should be near ten from the northern hemisphere and fifteen 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 positions and rates listed below are exact
for Saturday night/Sunday morning April 17/18. 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 elusive Pi Puppids (PPU) are now active from a radiant located at 07:12 (108) -46. This
area of the sky lies in western Puppis near the double star Iota Puppi. This radiant is best placed
as soon as it becomes dark as it culminates during the afternoon hours when the sun is still above
the horizon. These meteors are nearly non-existent away from the night of April 23rd. Even on that
night it would be lucky to spot just one, especially from the northern hemisphere, where the radiant
lies low in the southwest at dusk. This shower has produced outbursts in the past so it should be
monitored whenever possible, especially from the southern hemisphere. With an entry velocity of only
18 km/sec., the average Pi Puppid meteor would crawl through the sky at a snails pace.

The team of Sirko Molau and Juergen Rendtel have discovered a weak radiant active at this time in
the constellation of Virgo. Video data shows that the Sigma Leonids (SLE) are active from
April 18th through the 25th with maximum activity falling on the evening of April 21st (22nd UT).
The radiant is currently located at 13:16 (199) +05. This position lies in central Virgo,
five degrees northeast of the third magnitude star Delta Virginis. The radiant is best placed near
midnight LDT, when it lies highest above the horizon. At 20km/sec. the Sigma Leonids would produce
obvious, slow meteors. Expected rates are less than one per hour no matter your location.

There is also a second new radiant active in Virgo this time of year. Video data shows that the
h Virginids (HVR) are active from April 22-25 with maximum activity occurring on the 22nd.
On the evening of the 21st (22nd UT), the radiant is currently located at 14:16 (214) -11. This
position lies on the Virgo/Libra border, two degrees southeast of the fourth magnitude star Kappa
Virginis. The radiant is best placed near 0200 LDT, when it lies on the meridian and is highest
above the horizon. At 24km/sec. the h Virginids would produce more obvious, slow meteors. Expected
rates would also be less than one per hour no matter your location.

The wide Antihelion (ANT) radiant is now centered at 14:40 (220) -16. This area of the sky
lies in western Libra, three degrees west of the second magnitude star Zubenelgenubi (Alpha
Librae). This radiant is best placed near 0200 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 Hydra,
Libra, or eastern Virgo 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.

The major shower known as the Lyrids (LYR) are active from April 16th through the 25th.
Maximum activity occurs on the morning of April 22th. The radiant is currently located at
18:00 (270) +35. This position actually lies in eastern Hercules, eight degrees southwest of the
brilliant blue-white zero magnitude magnitude star known as Vega (Alpha Lyrae). The radiant is best
placed during the last dark hour before dawn, when it lies highest above the horizon. At 48km/sec. the
Lyrids would produce meteors of medium velocity. Expected rates this weekend are near one per hour
during the last dark hour before dawn. At maximum, hourly rate between 10-20 can be expected. Due
to the northerly declination of the radiant, these meteors are not well seen from high southern
latitudes.

The team of Sirko Molau and Juergen Rendtel have a third weak radiant active at this time in
the constellation of Cygnus. Video data shows that the Nu Cygnids (NCY) are active from
April 18th through May 7th. Maximum activity occurs on the morning of April 20th. The radiant
is currently located at 20:08 (302) +38. This position lies in central Cygnus, four degrees
southwest of the second magnitude star Sadr (Gamma Cygni). The radiant is best placed during the
last dark hour before dawn, when it lies highest above the horizon in a dark sky. At 42km/sec. the
Nu Cygnids would produce meteors of medium velocity. Expected rates are near one per hour during
the last dark hour before dawn. Due to the northerly declination of the radiant, these meteors are
not well seen from south of the equator.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately seven
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 thirteen 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.