Meteor Activity Outlook for February 20-26, 2010
February 21, 2010
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 first quarter phase on Monday February 22nd. At this time the moon lies 90 degrees east of the sun and sets around midnight local standard time (LST). 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 ~12 from the northern hemisphere and ~15 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 21/22. 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 11:00 (165) +05. This area of the sky lies in a remote area of southwestern Leo. The nearest star that is easily visible is 4th magnitude Sigma Leonis, located 5 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 ~ 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 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 < 1 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.
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 11h 00m +05 30 2 2 ACE Alpha Centaurids 15h 03m -63 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