BTW - the following monthly advisory is published on the MeteorObs mailing list:
From: meteorobs-bounces@meteorobs.org [mailto:meteorobs-bounces@meteorobs.org] On Behalf Of Robert Lunsford
Sent: 04 February 2010 20:31
To: meteorobs@meteorobs.org
Subject: (meteorobs) Meteor Activity Outlook for February 6-12, 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 wanes from a fat crescent phase to nearly new. The moon will be a bit of a problem this weekend but observers can overcome the glare by keeping the moon out of their field of view. As the week progresses the moon approaches the sun and becomes less of a problem with each passing night. The estimated total hourly rates for evening observers this week is near three no matter your location. 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 6/7. 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 10:04 (151) +10. This area of the sky lies in southwestern Leo, very close to 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) reach 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 near five per hour but outbursts with higher rates have been reported in the past. The current radiant position lies at 13:52 (209) -59. This position lies in southeastern Centaurus, three degrees northwest of the brilliant zero magnitude star 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 have revealed a radiant active in extreme eastern Hydra this time of year. The Pi Hydrids (PIH) are only active for five nights and reach maximum activity on Monday February 8th. Hourly rates on that morning should be near one shower member per hour as seen from the southern hemisphere. Northern observers would most likely see slightly less than one per hour. The first signs of activity from this radiant appear on the morning of February 4th. The current radiant position lies at 14:15 (214) -24. This position lies near the intersections of the constellations Hydra, Virgo, and Libra, three degrees northeast of the third magnitude star Pi Hydrae. The radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. At 70km/sec. the Pi Hydrids would produce mostly swift meteors.
Another discovery 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 first signs of activity from this radiant appear on the morning of February 10th. The radiant position on the 12th lies at 16:24 (246) +24. This position lies in western Hercules, three degrees 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)) - 10:04 (151) +10 Velocity - 30km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr.
Alpha Centaurids (ACE)) - 13:52 (209) -59 Velocity - 56km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - 5 per hr.
Pi Hydrids (PIH) - 14:15 (214) -24 Velocity - 70km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - 1 per hr.
Beta Herculids (BHE) - 16:24 (246) +24 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:
www.amsmeteors.org/showers.html#X2009
Clear Skies!
Robert Lunsford
American Meteor Society
Phil.
  