Meteor Activity Outlook for February 13-19, 2010
February 13, 2010 6 Comments
The Meteor Activity Outlook is a weekly summary of expected meteor activity written by Robert Lunsford, Operations Manager of the American Meteor Society and contributor to this blog. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.
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 ~2 for those in the northern hemisphere and ~3 for those south of the equator. For morning observers the estimated total hourly rates should be ~14 the northern hemisphere and ~20 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.
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 ~ 2 per hour no matter your location. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.
Alpha Centaurids (ACE)
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 < 5 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.
Beta Herculids (BHE)
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 ~ 1 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.
The list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning.
Shower Name RA DEC Vel Rates km/s NH SH ANT Antihelions 10h 32m +07 30 2 1 ACE Alpha Centaurids 14h 28m -61 56 <1 3 BHE Beta Herculids 16h 32m +22 56 1 <1 RA - Right Ascension DEC - Declination Vel - Velocity relative to Earth (in km per sec) Rates - Rate of visible meteors per hour from a dark site NH - Northern Hemisphere SH - Southern Hemisphere