(meteorobs) Meteor Activity Outlook for February 13-19, 2010

Robert Lunsford lunro.imo.usa at cox.net
Fri Feb 12 09:48:26 EST 2010


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 new phase on Sunday February 14th. At this time the moon lies near the sun and is invisible
at night. Next week the waxing crescent moon will enter the evening sky but will set long before the more productive morning hours
arrive. 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 fourteen from the northern
hemisphere and twenty 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.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning February 13/14. 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 10:32 (158) +07. This area of the sky lies in southwestern Leo, seven
degrees southeast of the first magnitude star Regulus (Alpha Leonis). 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,
Cancer, Sextans, or extreme western Hydra 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 Alpha Centaurids (ACE) reached maximum activity on Monday February 8th. 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 five per hour, even with the radiant located high in the sky. The current radiant position
lies at 14:28 (217) -61. This position lies in southeastern Centaurus, directly between the brilliant stars Rigel Kentaurus (Alpha
Centauri) and Hadar (Beta 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.

Studies by Sirko Molau and Juergen Rendtel of video radiants has revealed a radiant active in Hercules this time of year. The Beta
Herculids (BHE) are only active for five nights and reach maximum activity on Friday February 12th. Hourly rates on that morning
should be near one shower member per hour as seen from the northern hemisphere. Those situated south of the equator should average
slightly less than one meteor per hour. The radiant position on the 14th lies at 16:32 (248) +22. This position lies in western
Hercules, just north of the third magnitude star Beta Herculis. 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 Beta Herculids would produce mostly swift meteors.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately eleven 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 fourteen 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 list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday
night/Sunday morning.

Antihelion (ANT)) - 10:32 (158) +07   Velocity - 30km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr.

Alpha Centaurids (ACE)) - 14:28 (217) -61   Velocity - 56km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - 3 per hr.

Beta Herculids (BHE) - 16:32 (248) +22    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 




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