(meteorobs) Meteor Activity Outlook for February 20-26, 2010

[Robert Lunsford]

February offers the meteor observer in the northern hemisphere a couple of weak showers plus falling sporadic rates. This may not 
seem too exiting but you never know when surprises are in store. An errant earthgrazer from the Centaurid complex may shoot 
northward. Better yet, a bright fireball may light up the sky. February is the start of the fireball season, when an abundance of 
fireballs seem to occur. This lasts well into April and seems to occur mostly during the early evening hours.

Observers in the southern hemisphere are treated to the Alpha Centaurid peak on the 8th plus the entire Centaurid complex of 
radiants is active all month long. Sporadic rates are slightly less than those seen in January, but still stronger than those 
witnessed north of the equator.

During this period the moon reaches its first quarter phase on Monday February 22nd. At this time the moon lies ninety degrees east 
of the sun and sets near midnight local standard time (LST). 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 twelve 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 February 21/22. 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 11:00 (165) +05. This area of the sky lies in a remote area of southwestern 
Leo. The nearest star that is easily seen is fourth magnitude Sigma Leonis, located five degrees east of the center of the radiant. 
This radiant is best placed near 0100 LST 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 western Leo, Sextans, Crater, or western Virgo could be a candidate for this shower. Rates 
at this time should be near two per hour no matter your location. With an entry velocity of 30 km/sec., the average Antihelion 
meteor would be of medium-slow speed.

The last of the Alpha Centaurids (ACE) are visible this weekend. This shower is only visible south of thirty degrees north latitude. 
The further one is located south (down to 60S) the better the radiant is situated in the sky. Expected rates from the southern 
hemisphere is now less than one per hour, even with the radiant located high in the sky. The current radiant position lies at 15:03 
(226) -63. This position lies in extreme southeastern Centaurus, five degrees southeast of the brilliant zero magnitude star Rigel 
Kentaurus (Alpha Centauri). The radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon 
in a dark sky. At 56km/sec. the Alpha Centaurids would produce mostly swift meteors.

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

Antihelion (ANT)) - 11:00 (165) +05    Velocity - 30km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr.

Alpha Centaurids (ACE)) - 15:03 (226) -63    Velocity - 56km/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#X2009

Clear Skies!
Robert Lunsford
American Meteor Society