(meteorobs) Meteor Activity Outlook for April 24-30, 2010

[Robert Lunsford]

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 full phase on Wednesday April 28th. At this time the moon lies opposite the sun and rises as 
the sun sets. This weekend the waxing gibbous moon will set before the start of morning twilight, allowing a brief opportunity to 
view the meteor activity under good conditions. This window of opportunity shrinks with each passing night and is closed by Tuesday 
morning April 27th. 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 24/25. 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 07:24 (111) -45. This area of the sky lies in south-central 
Puppis near the third magnitude star Sigma Puppis. 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 13:51 (208) +04. This position lies in eastern Virgo, four degrees 
northwest of the fourth magnitude star Tau Virginis. The radiant is best placed near midnight local daylight time (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 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 15:08 (227) -18. This area of the sky lies in central Libra, five degrees 
southeast of the second magnitude star Zubenelgenubi (Alpha Librae). 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 
extreme eastern Hydra, Libra, northern Lupus, western Scorpius, 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 occurred on the morning of 
April 22th. The radiant is currently located at 18:16 (274) +32. This position lies on Hercules/Lyra border, 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. 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 occurred on the morning of April 20th. 
The radiant is currently located at 20:56 (314) +43. This position lies in central Cygnus, three degrees southeast of the first 
magnitude star Deneb (Alpha 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 list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday 
night/Sunday morning.

Pi Puppids (PPU) - 07:24 (111) -45   Velocity - 18km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Sigma Leonids (SLE) - 13:51 (208) +04   Velocity - 20km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

h Virginids (HVR)- 14:16 (214) -11    Velocity - 24km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Antihelion (ANT) - 15:08 (227) -18   Velocity - 30km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - 2 per hr.

Lyrids (LYR) - 18:16 (274) +32   Velocity - 48km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - <1 per hr.

Nu Cygnids (NCY) - 20:56 (314) +43   Velocity - 42km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - <1 per hr.

*For a detailed explanation on the different classes of meteor showers and other astronomical terms, please visit: 
http://www.amsmeteors.org/showers.html#X2010

Clear Skies!
Robert Lunsford
American Meteor Society